Interest in the gastrointestinal (GI) factors of autistic disorder (autism) has developed from descriptions of symptoms such as constipation and diarrhea in autistic children and advanced towards more detailed studies of GI histopathology and treatment modalities. This review attempts to critically and comprehensively analyze the literature as it applies to all aspects of GI factors in autism, including discussion of symptoms, pathology, nutrition, and treatment. While much literature is available on this topic, a dearth of rigorous study was found to validate GI factors specific to children with autism.