Children with typical autism, other early childhood psychoses and severe mental retardation without autistic behaviour were identified in an epidemiological study in an area of South East London. The social class distribution of their fathers was examined and no significant differences were found between the groups, nor in a comparison with the general population of the area. Fathers of children with autism and related conditions referred to an out-patient clinic with a special interest in autism, mostly at their own request, and fathers joining the National Society for Autistic Children, were of higher social class than both the average for England and Wales and the fathers of the study children. Joining the NSAC during its early years, and keeping up membership were also linked with higher social class. The findings supported the view that reports of a social class bias in autism may be explained by factors affecting referral and diagnosis.