Vancouver is a numbered referencing style. This guide to Vancouver is based on Citing medicine: the NLM style guide for authors, editors & publishers.

There are two main elements in the Vancouver citation style: in-text citations in your paper and the reference list at the end of your paper.

The in-text citation 

Unique reference number

A number in parentheses is inserted in your text at the point where you refer to (cite) your source of information. In-text citations go after full stops and commas, but before colons and semicolons. 

See this example:

An unhealthy diet, obesity and physical inactivity play a role in the onset of Type 2 diabetes,(1) but it has been shown that increased physical activity substantially reduces the risk,(2) and participation in regular physical activity is one of the major recommendations of the evidence based guidelines for the primary prevention of diseases.(1) 

Each time a new source is cited, it is allocated the next consecutive number. This number becomes the unique identifier of that source and is re-used each time that particular reference is cited in the text.
 

When multiple references are cited at the same place in the text, use commas without spaces to separate non-inclusive numbers in chronological order.

            Example:  Multiple studies have indicated…(1,3,5,10) 

If multiple references cited at the same place in the text are inclusive, use a hyphen to join the first and last numbers.

            Example:  Multiple studies have indicated that…(1-3) 

Author/editor names

Examples with author names in the text of the document:

One author: Doe(7) reported on the survey...

Two authors: Avery and Williams(5) research demonstrates...

More than two authors, or authors and a group: include the first author’s surname followed by “et al.” or “and others”:

Doe et al.(9) reported on the survey....

Note: Do not use the possessive form 'et al's' - rephrase the sentence.

The reference list 

Every source which has an in-text citation should also be listed in the reference list at the end of your document. Reference list entries contain all the information that someone needs to follow up your source.

References are listed numerically at the end of the body of work. All journal titles must be abbreviated as per the National Library of Medicine's (US) PubMed website within their NLM catalog: Journals referenced in the NCBI database. 

If using EndNote you can install the Medicine Journal Terms List, which includes over 14,000 journal title abbreviations. 

Author/editor names

Citing Medicine lists all authors/editors in the reference list, however they do state “The following formats are not NLM practice for citing authors, but are acceptable options: If space is a consideration, the number of authors may be limited to a specific number, such as the first three authors or first six authors. Follow the last named author with a comma and “et al.” or “and others”. Check with your Unit Coordinator for more information.
 

One to six authors/editors : List all in the reference list:

1. Avery M, Williams F. The importance of pharmacist providing patient education in oncology. J Pharm Pract [Internet]. 2015 [cited 2016 Jan 27];28(1):26-30. Available from: https://journals.sagepub.com/doi/full/10.1177/0897190014562382

More than six authors/editors: List the first six authors/editors then et al.:

2. de Lima M, McNiece I, Robinson SN, Munsell M, Eapen M, Horowitz M, et al. Cord-blood engraftment with ex vivo mesenchymal-cell coculture. N Engl J Med.[Internet]. 2012;367(24):2305-15. Available from: https://www.nejm.org/doi/full/10.1056/NEJMoa1207285 

No author or editor: List the title first:

3. Prevention strategies for asthma: secondary prevention. CMAJ [Internet]. 2005 [cited 2016 Feb 3];173(6) Suppl:s25-7. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC1329949