A survey of approximately 4,000 questionnaires completed by parents of autistic children provided ratings on a variety of treatments and interventions. Among the biomedical treatments, the use of high-dosage vitamin B6 and magnesium (n = 318) received the highest ratings, with 8.5 parents reporting behavioral improvement to every one reporting behavioral worsening. Deanol (n = 121) was next most highly rated, with 1.8 parents reporting improvement to each one reporting worsening. Fenfluramine (n = 104) was third, with a ratio of 1.5:1. Thioridazine hydrochloride (Mellaril), by far the most often used drug on the list (n = 724), was fourth with a helped-worsened ratio of 1.4:1. The research literature on the use of vitamin B6-magnesium is briefly reviewed, and mention is made of recent findings regarding high-dosage folic acid in autism and biotin in Rett syndrome.