Development and behavior during the first 2 years of life was assessed retrospectively by the parents to 23 adolescents and young adults with Asperger syndrome and 13 typically developing adolescents and young adults. The groups were matched on chronological age and the participants were within the normal range of intelligence. The questionnaire, symptoms of autism before the age of 2 (SAB-2) comprised seven areas: contact and social activity, responses to sensory perceptions, communication and language/speech, food/feeding and sleep, play and fixations/rituals, movements and motor skills, and development and behavior. An eighth area of possible early suspicions was also part of the questionnaire. There were significant differences between the groups in all the areas and that the parents in many cases were well aware of anomalies in their children's behavior at an early age. Food/feeding and sleep and contact and social activity were found to be the areas that caused most concern. The SAB-2 was also judged to be a valid and reliable instrument for retrospective assessment of infants. (Contains 4 tables and 1 figure.)