Gonosomal aberrations such as Turner's syndrome are frequently associated with autoimmune diseases or with serological markers for autoimmune diseases. An autoimmune origin has been suggested for alopecia areata. The simultaneous occurrence of alopecia areata and Turner's syndrome has not formerly been reported. We present here four female patients with Turner's syndrome, who also developed typical alopecia areata. In three of these cases alopecia areata first appeared during adolescence, whilst the fourth patient showed an early manifestation at the age of 10. Two of the patients had alopecia areata of the ophiasis type, while the condition was localized in one and diffuse in the fourth. In addition, two of the patients had diffuse hypotrichosis of the scalp and reduced sweat gland activity, with no other signs of ectodermal dysplasia. The third patient had not develop body hair after her childhood, except for some sparse thin hair in the axilla and in the genital area. The coincidence of alopecia areata and Turner's syndrome may indicate some genetic relationship between the two entities.