ABSTRACT. Previous studies have suggested that children with autism spectrum disorders (ASD) may have different medical histories than nonspectrum children in several areas: their reactions to vaccinations, number of ear infections, chronic gastrointestinal problems, and use of antibiotics. Furthermore, some studies have found associations between regressive autism and gastrointestinal (GI) symptoms. The present study analyzes the medical records from birth to the age of 2 years of 99 children (24 typically developing; 75 with ASD, of whom 29 had parent-reported regression). Data were coded in the following areas: frequency and purpose of pediatrician visits, frequency and type of illnesses and medications, type and chronicity of GI complaints, date of vaccinations, growth data, and whether the pediatrician noted behaviors indicative of an ASD before the age of 2 years. Children with ASD were found to have significantly more ear infections than the typically developing children as well as to use significantly more antibiotics. Typically developing children had significantly more illness-related fevers. There was a nonsignificant trend toward the ASD group having more chronic gastrointestinal problems. There were no significant differences between the groups for the age of vaccination or for number of pediatrician visits. Finally, pediatricians noted symptoms of onset of possible autism, including language delay, for 44 of the 75 children with ASD and 2 of the 24 typical children. Results are discussed in terms of needs for future research.