Kaposi's sarcoma (KS) is very unusual in Caucasian women with AIDS. We conducted a retrospective survey of 12 female AIDS patients with KS, including 11 Caucasian women. HIV infection was thought to have been acquired after sexual contact, intravenous drug use (nine cases) or blood transfusion (three cases). In these patients KS was often the first manifestation of AIDS and showed an aggressive course. The disease was associated with a severe immunodeficiency (CD4 T lymphocyte count less than 100 x 10(6)/l in 50% of cases) and a poor prognosis. In four patients, lesions first developed on areas of sexual contact, supporting the hypothesis that KS is a sexually transmitted disease.