The autistic spectrum disorder (ASD) is a neurodevelopmental disorder characterized by socially aloof behavior and impairment of language and social interaction. This paper is a review of literature on gastrointestinal problems in children with ASD. Gastrointestinal symptoms are described in 9-54% of autistic children, among which most common are: constipation, diarrhea and abdominal distension. The gastro-intestinal abnormalities reported in autism include: inflammation (esophagitis, gastritis, duodenitis, enterocolitis) with or without autoimmunity, lymphoid nodular hyperplasia, increased intestinal permeability, low activities of disaccharidase enzymes, impairment of detoxification (e.g. defective sulfation of ingested phenolic amines), dysbiosis with bacterial overgrowth, food intolerance or exorphin intoxication (by opioid derived from casein and gluten). A beneficial effect of dietary intervention on behavior and cognition of some autistic children indicates a functional relationship between the alimentary tract and the central nervous system. There are no epidemiologic data concerning the incidence or prevalence of gastrointestinal problems within the population of children with ASD in comparison to the population of non-ASD children.