Eighty-one parents of 42 autistic probands and 34 parents of 18 Down syndrome probands were examined using a semistructured, investigator-based version of the Schedule for Affective Disorders and Schizophrenia Lifetime Version to estimate the lifetime risk of psychiatric disorder. The lifetime prevalence rate of anxiety disorder was significantly greater in parents of autistic probands than in parents of Down syndrome probands. The lifetime prevalence rate of major depressive disorder, while not significantly different in cases and controls, may be high in the parents of autistic probands (27%) in comparison with populations rates.