Treatment of autistic disorder and other pervasive developmental disorders (PDDs) requires identification of target symptoms, such as irritability, hyperactivity, self-injurious behavior, anxiety, or depression. If the target symptoms adhere to a comorbid syndrome such as obsessive compulsive disorder, treatment is specific to that comorbid syndrome with some exceptions. It is important to distinguish hyperactivity and inattention caused by difficulty with language and social impairment or rituals of autistic disorder and other PDDs from that caused by a comorbid syndrome similar to attention-deficit hyperactivity disorder. Psychopharmacologic classes discussed include potent serotonin transporter inhibitors (e.g., clomipramine and fluoxetine), other tricyclic antidepressants, stimulants, sympatholytics (clonidine and β-blockers), naltrexone, fenfluramine, typical (e.g., haloperi- dol) and atypical (e.g., clozapine and risperidone) neuroleptics, anticonvulsants (e.g., carbamazepine and sodium valproate), lithium, anxiolytics, pyredoxine, and newer agents.