OBJECTIVE: To evaluate the proposed link between the administration of the measles, mumps, and rubella (MMR) vaccine and the development of autism. DATA SOURCES: A literature search utilizing MEDLINE (1966–November 2003), with the key terms measles, mumps, rubella, and autism, was conducted. Review of the references listed in the articles identified was also performed. DATA SYNTHESIS: Ten articles that specifically evaluated the possible relationship between the MMR vaccine and autism were identified. Review articles, commentaries, and evaluations of a link between gastrointestinal symptoms in autistic children and MMR immunization were excluded. CONCLUSIONS: Based upon the current literature, it appears that there is no relationship between MMR vaccination and the development of autism.