An 11 year old diagnosed with pervasive developmental disorder, mental retardation, and pica was treated for symptoms of aggression, irritability, self-injurious behavior, motor overactivity, and inattention in an open prospective sequential medication trial comparing baseline (3 months), propranolol (2.4 mg/kg/day for 4 months), and subsequent nadolol (2.4 mg/kg/day for 5 months). Significant differences were found favoring nadolol over propranolol or baseline on measures of inattention, motor overactivity, and self-injurious behavior. Aggression and irritability were rated most improved by teachers during nadolol treatment. No effects of beta-blockers on pica were observed. Results are considered suggestive and preliminary because no placebo controls, blind ratings, or treatment reversal withdrawal design were used. Nadolol may have appeared more effective than propranolol because it is more potent or because treatment duration was longer. Peripheral beta-adrenergic blockade may be useful in certain children with autistic disorder, but systematic studies are needed before its routine use in children can be recommended.