The case of a young man is presented who initially appeared to be quite normal and very intelligent, if somewhat immature. Profound prosopagnosia was discovered in the course of a psychological assessment. Closer investigation revealed definite autistic features of the Asperger type, and both conditions ran in the family in a milder form. Questions arising from observations and experiments as well as from the case history are discussed, and an attempt is made to elucidate some problems in the light of the original theories about these conditions. It is suggested that prosopagnosia may be an essential symptom in one of the autism spectrum disorders, perhaps of a specific subgroup of Asperger syndrome. Visual hypo-emotionality is suggested as a possible common denominator of the two conditions.