Purpose: To describe autistic spectrum disorders (ASDs) in a cohort of children with history of unprovoked seizures other than infantile spasms in the first year of life. Methods: The source of data was computer records from all the three pediatric departments in Iceland. Children diagnosed 1982-2000 with unprovoked seizures with onset between 28 days and 12 months of age (N = 102) were invited to participate in a study. Children with known developmental disorders and those whose parents had concerns regarding their child's development or behavior were investigated for possible ASD. Parents were asked to complete the Social Communication Questionnaire and children scoring 10 points or higher were further examined with the Autism Diagnostic Interview-Revised and observational measures. Results: Eighty-four children (82.4%), 28 boys and 56 girls, participated in the study and 36.9% (31/84) were investigated for possible ASD. Twenty-four (28.6%) had at least one neurodevelopmental disorder, 14.3% had mental retardation (MR), and six (7.1%) were diagnosed with ASD, all of whom also had MR and three of whom had congenital brain abnormalities. Conclusion: These results suggest that the estimated prevalence of ASD is higher in children with history of seizure in the first year of life than it is in the general population. There are indications that support the view that children with ASD and history of seizure in the first year of life have higher prevalence of congenital brain abnormalities and are more often female, than other children with ASD.