Objectives: To examine indexed health science journals to evaluate the prevalence of Wikipedia citations, identify the journals that publish articles with Wikipedia citations, and determine how Wikipedia is being cited.

Design: Bibliometric analysis.

Study selection: Publications in the English language that included citations to Wikipedia were retrieved using the online databases Scopus and Web of Science.

Data sources: To identify health science journals, results were refined using Ulrich's database, selecting for citations from journals indexed in Medline, PubMed, or Embase. Using Thomson Reuters Journal Citation Reports, 2011 impact factors were collected for all journals included in the search.

Data extraction: Resulting citations were thematically coded, and descriptive statistics were calculated.

Results: 1433 full text articles from 1008 journals indexed in Medline, PubMed, or Embase with 2049 Wikipedia citations were accessed. The frequency of Wikipedia citations has increased over time; most citations occurred after December 2010. More than half of the citations were coded as definitions (n = 648; 31.6%) or descriptions (n=482; 23.5%). Citations were not limited to journals with a low or no impact factor; the search found Wikipedia citations in many journals with high impact factors.

Conclusions: Many publications are citing information from a tertiary source that can be edited by anyone, although permanent, evidence based sources are available. We encourage journal editors and reviewers to use caution when publishing articles that cite Wikipedia.