In the context of an epidemiological study of autism in Nova Scotia, subjects were evaluated for minor physical anomalies and physical measurements. Normal control children, children with autism and their siblings, and children with developmental disabilities and their siblings were compared. Posterior rotation of the external ears was found to be a characteristic related to autism specifically, rather than to developmental disabilities in general. Small feet and normal-to-large hands also were observed in the autism group. Children with autism had a significant reduction in interpupillary distance, but not intercanthic distance or head circumference. In contrast, children with other developmental disabilities were notable for general small stature, which affected the hands, feet, eyes, and head size, as well as height. Abnormal ear configuration was the minor malformation most characteristic of the developmental disability group, and the subset of Down syndrome children had single transverse creases of the palm and epicanthic folds that resulted in significantly increased rates of these anomalies in the developmentally disabled controls. Siblings of the two disabled groups were not significantly different from normal controls on any of the measures that characterized children with autism or other developmental disabilities. The results agree with those of several previous studies, which have suggested that abnormalities of the ears are the general category of minor anomalies most associated with autism. Recent evidence regarding the embryological origin of autism suggests that the ear effects may be an important marker of the initiating events that lead to the disorder.