Safety and Efficacy Study in the Treatment of Intestinal Problems Associated With Autism

Inclusion Criteria: * Male or female from 2 years to 18 years of age (up to, but not inclusive of the 18th birthday) * Diagnosis of autistic disorder corroborated by an Autism Diagnostic Interview - Revised (ADI-R) assessment performed by a certified investigator * Physician Clinical Global Impression of Severity (of Autistic Disorder) * History of chronic, persistent gastrointestinal disturbance * No elective changes in medication, diet intervention, or behavioral therapy during the study (18 weeks total) Exclusion Criteria: * Evidence of a gastrointestinal infection or GI abnormality * A known diagnosis of other gastrointestinal pathology * Antibiotic and/or antifungal (e.g. nystatin) medication * Chelation therapy * Medication affecting gastrointestinal transit * Planned use of prohibited drugs or agents that could affect GI transit * Changes in diet intervention within 30 days prior to the screening visit * Changes in alternative medical therapies or dietary supplements within 30 days prior to the screening visit * Adding and/or changing behavior modification or psychotherapy during participation in the study * Adding or changing psychotropic medication during participation in the study * DSM-IV diagnosis of a pervasive developmental disorder other than autistic disorder * Evidence of a seizure disorder, diagnosis of fragile X syndrome, tuberous sclerosis complex, liver disease, pancreatic disease, cystic fibrosis, or chronic infection * Previous gastrointestinal surgery * Pregnancy * Participation in another investigational study * Significant deviation from normal laboratory test values at baseline * IgA deficiency (serum IgA \< 5 mg/dL) * A history of severe hypersensitivity to human immunoglobulin * Treatment with any human immunoglobulin and/or immunoglobulin products * Any concurrent medication that would compromise subject's tolerance of drug or compliance with the protocol