How to Write the Introduction of a Research Paper

The introduction explains why the study was done: it moves from the broad context to the specific gap and ends with the objective or hypothesis. A good introduction is short, usually three to five paragraphs, and prepares readers for the Methods.

The funnel structure

1. Context: what is the condition or topic, and why does it matter (burden, importance)?
2. What is known: the most relevant, recent evidence.
3. The gap or problem: what is unknown, uncertain or conflicting.
4. The objective or hypothesis: exactly what this study set out to do.

Writing tips

• Cite recent, high-quality sources, including systematic reviews, and cite accurately.
• Be selective: include only what the reader needs to understand the objective.
• State the gap specifically, not "few studies exist".
• Avoid results, conclusions and extended literature reviews.
• Make sure the objective matches the primary outcome in Methods and the main result in Results.

Illustrative example

Invented for teaching. "Delirium after hip fracture surgery affects up to one in four older patients and is linked to longer stay and loss of independence. Early surgery is recommended in guidelines, but evidence on whether timing within 48 hours reduces delirium is inconsistent, and most data come from single large centres. We therefore examined whether surgery within 48 hours was associated with lower delirium in a regional hospital." (Invented example; statistics illustrative.)

Checking it

Underline the sentence that states the gap and the sentence that states the objective. If either is missing or vague, revise. Check that each cited statement is supported by the source.

Common pitfalls

• A history of the disease from antiquity to today.
• Claiming no previous research exists without a search.

Key takeaways

• Context, evidence, gap, objective.
• Short, focused and honest.

This page is general educational information about research methods. It is not medical, legal or regulatory advice; follow your institution's ethics board and your target journal's instructions.