PROTOCOL ENTRY CRITERIA:

--Disease Characteristics--

Meets diagnostic criteria for autism

--Prior/Concurrent Therapy--

Other:

• At least 3 months since prior electroconvulsive therapy
• At least 1 month since prior investigational drugs or treatment with any drug known to cause major organ toxicity
• At least 2 weeks since prior monoamine oxidase inhibitors
• At least 6 weeks since prior long acting phenothiazines
• At least 1 week since prior other psychotropic drugs
• No prior fluoxetine of 20 mg/day for 6 weeks
• At least 6 weeks since prior fluoxetine
• No concurrent use of terfenadine (Seldane) or astemizole (Hismanal)
• No concurrent electroconvulsive therapy or other psychotropic drugs (unless otherwise permitted)
• Prior participation in another serotonin reuptake inhibitor trial allowed

--Patient Characteristics--

Hematopoietic: No significant hematopoietic disease

Hepatic: No prior or concurrent liver disease

Renal: No prior or concurrent kidney disease

Cardiovascular:

• No significant cardiovascular disease
• No abnormal EKG

Neurological:

• No prior seizure disorder or high risk development of seizures
• No prior cerebrovascular disease
• No prior brain trauma

Other:

• Not pregnant or nursing
• Negative pregnancy test
• No unstable major medical illness or systemic disease
• No moderate or severe mental retardation and motor deficits (IQ less than 50)
• No family history of bipolar disorder
• No prior or concurrent other mental disorders (e.g., schizophrenia, schizoaffective, organic, or bipolar disorders)
• No significant autoaggressive behavior or serious suicidal risk
• No prior or concurrent gastrointestinal conditions
• No unstable endocrine disease (e.g., hypo or hyperthyroidism)
• No prior or concurrent malignancy
• Must be able to tolerate tapering of psychoactive medication
• No history of hypersensitivity or severe side effects to fluoxetine or other serotonin reuptake inhibitors
• No history of severe personality disorder or noncompliance