How to write an Introduction for a Research Paper

EDIT: This webpage was created in Jan 2018 as part of a writing week I was teaching. Since then many students have told me that they would like a general guide book for new scientists. I have now created that book. You can check it out here.

You can download the updated version of this page below (with marginally improved cartoons) or you can read on to see the original version

Writing the “Introduction” to your research paper / project report / manuscript or lab report sets the tone for the rest of the work and gets the reader/ marker/reviewer/editor to start thinking about the things you want them to. Hopefully this will establish a favourable opinion that will carry through to your marks/response.  This guide will talk you through how to write an introduction for a research paper; all the important, features that will ensure that you make the most of this important section.

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Big tip #1 this is the introduction to your work, not a general recap of the field

The goal of your intro is to bring everyone reading it up to speed as rapidly as possible. It is not supposed to be a comprehensive review of the literature, rather it should be focused and directly related to your study.

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Plan your story before you start your intro

One point before you begin; to be able to write an intro well you need to know what your main story is! What it is that you are actually introducing? Realistically, you will have a good idea where you are going, so: do the reading, take a bunch of notes of the important things you need to discuss, and sketch out a framework then come back to your intro once you have a better concept of where you are going. If you haven’t already, prepare your figs and write your results then come back here (my results writing guide available here, figures and figure legends here)

A quick note on PhD thesis/dissertation prep; The core concepts covered below are translatable into your thesis intro. However, the extended length of a thesis means there are some differences; I’m going to write a separate page about theses/dissertations soon which will go over some of the different things you need to address.

Big Tip #2 – Make sure to cover the four key objectives.

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Whenever I have asked a new writer what the point of the intro to their research paper is, they say that it’s to tell the reader all the information they need to be able to understand your work and therefore why you did it.  This is true, but it only really sums up part of your goal. Importantly, if you only think about the intro in this way,  you run the risk of your writing  being ineffective, boring and unfocused.

You actually have four objectives.

  1. The big picture (the context of your work, why it matters)
  2. Map the Gap in the literature that your work will fill
  3. Establish the aim(s) or hypotheses you will test
  4. Set up the discussion

The difference between a good intro and an OK intro is that whereas the OK intro tells the reader things that are known, the good intro frames the information in a way to highlight what isn’t known. It maps the gap in the literature. This should be done in a way that makes the questions that your work addresses the ones that are the most pressing.

IF you can do this well, it will leave the reader wanting to know the answers to the questions that you have asked.  The reader will therefore want to move on to your results. If you do this really well the reader will be interested in finding out about your findings, this is much better than them just understanding why you are interested.

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The other thing an intro needs to do is set up the discussion. This is important. If you need to bring in key concepts around which you will interpret your data it’s much better if you have laid the groundwork in the intro. So really you should start thinking about your discussion now and ideally write them alongside each other (discussion guide here. )


If you are writing for a specific journal or assignment, check the specific requirements. The biggest problem new writers have is that they make it too long, go too wide or into too much detail that isn’t really necessary. My recommendations are;

  • ~1 single spaced page = ~400-900 words only
  • 4-6 paragraphs only
  • No subheadings
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The standard approach is to start wide and become more and more focused and more and more specific as you move through.

Think about the journal target audience; the intro for a multi-discipline journal generally needs to start wider than in a more specialised area.

Write in paragraphs, think in paragraphs!

This should be obvious but if it is a long time since your last English class you might not have thought about it. Brief recap below…

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First sentence of each paragraph (topic sentence) should cover in simple terms, the main point you want to deliver. Then drop in your “token” sentences, the key findings that you need the reader to know. Link these together with a softer, easier sentence that stays on message. Avoid having more than two token sentences back to back. Finally, wrap it all up; make this a forward looking sentence that not only reiterates the topic sentence but also connects it to the following one. No more than one key point per paragraph!

Think about who you are writing for and how they will absorb your work. Writing in an accessible way is good for everybody and you need to write as if everyone will read all of it. However, realistically, faculty and even senior postdocs will already know most/all of what you are writing about. So, they are likely to be skim reading your intro. Skim readers might only read the first line of each paragraph, absorb that point then move on. Make sure your topic sentences work for you.

Paragraph One 

On message right from the start please. Not too wide! By the end of paragraph one your readers should have a good idea what the big question is – why they should care.

Start with a big impact statement…

Big Tip #3 In your first sentence; use a key-word from the title.

What is your paper actually about? Start there and don’t go wider. If you force yourself to do this you will get on message right from the off and avoid adding an extra paragraph of super wide stuff. (Not written a draft of your title yet? our guide for that is here)

If your study is directly related to a specific disease or tissue function then these are the easiest to write so consider starting there. However, if the work is actually focused on the function of a specific protein family or mechanism then introduce them up front in the first sentence and come back to the disease.

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In your first paragraph you should sell why this study is a big deal; what’s the endgame? Where will the work lead? You want the reader to care as soon as possible, I don’t mean the specific question here, more the overarching bigger problem.

For example, most intros about a disease will mention the effect it has on people’s quality of life, how many people are affected, what it costs etc. But, Map the Gap. The better intros, will also point out where the problems are; is there no effective therapy?  would a new diagnostic or prognostic marker help? where is the big hole? Don’t leave this paragraph without the reader knowing why they should care.

Big Tip #4 Last sentence of first paragraph – point out a problem/hole in the knowledge that your research paper will fill

Example first paragraph with generic terms!

Here is a disease, it’s bad, it affects X amount of people. We know this about the disease and how it works and more recently this other thing was discovered that is interesting. However, we still don’t know whatever your study relates to in a broad sense and knowing this would really help.

In paragraph 1 you can generally rely on citing a few good review articles as you will be talking at a high level. I try to make a point of referencing work from different authors, competitors and collaborators.

Paragraphs 2, 3 and 4

OK, you’ve established the big picture, next you are going to start to go deeper, always moving toward the specific questions your study addressed.

Before you begin, write down what it is you need the reader to know. This shouldn’t be a list of everything you know  –  think about what is relevant to your current story! Put your list in order of importance in relation to your study.

Big tip #5 Reading just the first sentence of each paragraph should be enough to understand the intro.

Take the most important points that you have identified and make them into the topic sentences that you will hang the rest of your paragraph around. Do this so you don’t lose focus. You don’t want to go off track here; if something is just an interesting aside it probably has no place in your intro. Order your topic sentences from broad to narrow… you need to focus your work toward the goal.

Remember the key is to map the gap about what is known about the specific problem before you did your experiments.

Example phrases;

  • “previously it has been reported that X affect Y but the molecular mechanism is unknown”
  • “An increase in Y has been correlated with disease progression but the pathogenic consequences have never been established
  • “Protein Y has been shown to be important for cell type B function Z, but its role in cell type C has not been evaluated

The underlined phrases are how you draw attention to where your research is going.

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Use primary refs here. Usually more than one per sentence (except topics). Again, make sure to cite your competitors and mention anywhere where there is controversy (especially important if your data supports or contradicts previous findings) – this will come in greater detail in the discussion but your readers should know a little about it up front and you can begin to make your case early. Remember that your reviewers will know the field too, so don’t try and ignore some previous work because it doesn’t fit your model.

By the end of this section your question should be obvious. If it’s not, tidy up, rephrase, reorder until it is!

Everyone’s approach is different, but I tend to overwrite this section then cut out and contract lots of the sentences during proofing. Each paragraph should end up <200 words.

Big Tip #6 Shorter intros are almost always better!

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Final paragraph

Finally, clearly state the obvious question/hypothesis/goal that you have been working toward. eg “The purpose of this study was to determine….” By including a sentence like this you will make it absolutely explicit what the reader is about to find out.

This sentence normally starts the last paragraph. You then follow it with sentences explaining your experimental rationale “….using X, Y and Z” You may want to say why this approach was used particularly if it is a new approach or new to this area.

Its quite common to end with a 1 sentence overview of the results and what they mean (in context with the big picture question you posed above).

And that’s it, you’re done. Go back and edit to make sure every sentence is helping set up your story and to cut out everything that doesn’t add value. Short and punchy will do more for your story than long and waffley. And that’s also why this guide is ending here!

Now go back and edit what you have written writing is an iterative process, it will take reworking and editing before you are finally happy. Remember you will need to connect your intro with your discussion so you will keep reworking both parts in concert with each other

Intro’s actually end up being one of the easier parts to write but like, all things, it takes practice so don’t worry if your first draft comes back with loads of comments!

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About the author

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Dr Kevin Hamill is a Senior Lecturer in Cell and Molecular Biology at the University of Liverpool, in the Department of Eye and Vision Science, Institute of Ageing and Chronic Disease. His lab focuses on cell-matrix interactions; you can read about ongoing work elsewhere on this blog, on the


lab webpages, or in his published work. As well as supervising PhD, Masters in Research and Undergraduate research projects, Kevin is the academic lead for the Lab skills Module of MRes Clinical Sciences program where he teaches fundamental skills for life scientists.

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