Background Smegma is widely believed to cause penile, cervical and prostate cancer. This nearly ubiquitous myth continues to permeate the medical literature despite a lack of valid supportive evidence.
Methods A historical perspective of medical ideas pertaining to smegma is provided, and the original studies in both animals and humans are reanalysed using the appropriate statistical methods.
Results Evidence supporting the role of smegma as a carcinogen is found wanting.
Conclusions Assertions that smegma is carcinogenic cannot be justified on scientific grounds.