PIP: This paper presents clinical data on 41 patients (29 male and 12 female) from Haiti who presented with acquired immunedeficiency syndrome (AIDS). Their mean age was 32 years (range 17-61 years). 4 of thes cases were homosexual or bisexual; none was an illicit drug user or a hemophiliac. In addition, 3 of the female patients had sexual contact with a male partner with AIDS. 4 patients had received blood transfusions before their illness. The most prominent clinical symptom in this series was chronic diarrhea of 2-33 months' duration, which occurrred in 39 patients (95%). Also reporte were marked weight loss (95%), fatigue (95%), prolonger fever (90%), and nodular or maculopapular skin lesions (54%). Opportunistic infections in this series included oroesophageal candidiasis (88%) and intestinal cryptosporidiosis (31%). Tuberculosis developed in 22% of patients. Immunologic evaluation revealed profoundly depressed T-helper cells and an inverted T-helper/T-suppressor cell ratio. Biologic markers included elevated alpha-1 thymosin and beta-2 microglobulin levels, elevated immune complexes, and the presence of acid-labile interferon. Of interest were differences in the clinical expression of AIDS between this series and cases in the US. The Haitian data suggest a higher incidencs of female cases,a predominance of gastrointestinal symptoms rather than respiratory symptoms and lymphadenopathy, a frequent association with tuberculosis, and a relatively low incidence of Kaposi's sarcoma or P. carinii pneumonia compared to the situation in the US. As in the US, where most AIDS cases are concentrated in New York and California, most AIDS cases in Haiti are found in residents of Port-au-Prince and Carrefour, which are centers for male and female prostitution.