A Study of RO5028442 in Adult Male High-Functioning Autistic Patients

Inclusion Criteria: * Patients with a diagnosis of Autistic Disorder as defined by DSM-IV, confirmed by the team and supported with the Autistic Diagnostic Observation Schedule (ADOS) * Male adults, 18 to 45 years of age * IQ \> 70 (Wechsler Adult Intelligence Scale-Full scale) * Body mass index (BMI) 18 to 35 kg/m2 inclusive * Aberrant Behavior Checklist (ABC) - Irritability subscale score \</= 13 Exclusion Criteria: * Positive urine test for drugs of abuse * Alcohol and/or substance abuse/dependence during the last 12 months * Positive for hepatitis B, hepatitis C or HIV infection * Clinically relevant cardiovascular, renal, hepatic or hematologic disease or disorder * Active inflammatory pulmonary disease * History of epilepsy/seizure disorder (except for simple febrile seizures) * Initiation of new or major change in psychosocial intervention within 4 weeks prior to randomization * Treatment with any investigational agent within 90 days prior to screening * History of hypersensitivity or allergic reactions