Fifteen children, 10 boys and 5 girls, with autistic disorder, were studied with low field magnetic resonance imaging (MRI). The age ranged from 2.7-13.1 years, with a mean of 8.3 years. All patients but one (who refused) had a normal CT scan of the C.N.S. The MRI investigation was performed during anaesthesia with a low field magnetic resonance imager. The cerebrum, cerebellum, and brain stem were examined. No pathological changes were found in any of the patients studied.