ABSTRACT. The prevalence of autistic spectrum disorder (ASD) in the United States is approximately 1 in 150 children. Many health care providers are unaware of parental beliefs and treatments, both medical and complementary, that parents use for their child with ASD. Understanding these beliefs and practices concerning diagnosis, cause, and utilization of medical and complementary care may help physicians provide better comprehensive care. Parents of children with ASD from 2 private practices-one in New York and one in New Jersey-were mailed a 6-page, self-administered survey. In addition to demographics and ASD type, the survey asked parents who diagnosed their child and if there was a perceived delay in that diagnosis; whether they believed there was any causal reason for their child's autism; what chronic symptoms, if any, their child experiences; and, if they had used any complementary and/or alternative therapies and at whose recommendation. Respondents included 77 of the 150 parents (51%) contacted. Most children were diagnosed by a neurologist and/or developmental pediatrician (54% and 47%, respectively). Average perceived delay in diagnosis was 18 months. Parents most frequently cited immunizations (54%), genetic predisposition (53%), and environmental exposure (38%) as a cause of their child's autism. Approximately half of children were reported as having at least one gastrointestinal, neurological, and/or allergic symptom; more than a third had immunological symptoms. Almost all parents (95%) indicated some use of complementary and alternative medicine (CAM) therapies, with most of the self-reported referrals generated from a physician or nurse (44%). Systemic complaints, parental beliefs, and use of CAM practices warrant open discussion by all health care professionals who provide care to this population.