Incidental findings arise when clinically relevant genetic information about a research participant or patient is identified outside the scope of the original research objective or diagnostic test being performed. These findings can relate to carrier status for a heritable condition, misattributed paternity or increased susceptibility to a medical condition. The decision whether to disclose these findings to the research subject or patient is underpinned by many ethical, moral, and potentially legal considerations. There is an urgent need for definitive guidelines for researchers and healthcare professionals. We performed a systematic review of the relevant literature concerning the disclosure of incidental findings, based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations, using the prescribed flowchart and checklist. At initial screening, 473 articles were retrieved. The inclusion and exclusion criteria aimed at obtaining data that were relevant and of sufficient quality were applied and a total of four relevant studies were identified, comprising 2,680 individual participants and 1,023 guidance documents. Major themes emerging from the included articles include patient autonomy, patient welfare, harmful secrets, and genetic literacy. The lack of relevant studies emphasizes the urgent need for empirical investigations into the disclosure or non-disclosure of genetic incidental findings, and the provision of guidelines to assist healthcare professionals and researchers. © 2012 Wiley Periodicals, Inc.