HIV infection/AIDS shows characteristic epidemiological and clinical patterns according to the region, country, and race. The epidemiological and clinical patterns of HIV infection/ AIDS in Korea was investigated by retrospectively analyzing the medical records of 176 HIV-infected persons who visited two major referral hospitals of AIDS in Korea from 1985 to April 2000. The most common transmission route was heterosexual contact (52.3%), followed by homosexual contact (23.9%). Among the opportunistic diseases, candidiasis was the most prevalent (21.6%), followed by Pneumocystis carinii pneumonia (15.9%), tuberculosis (12.5%), and CMV infection (9.1%). The most common initial AIDS-defining opportunistic disease was tuberculosis (33.3%). The most common causes of death were tuberculosis (25.7%) and Pneumocystis carinii pneumonia (25.7%). This study describes the epidemiological and clinical patterns of HIV infection/AIDS in Korea, which not only enables us to accurately understand HIV infection/ AIDS in this country, but eventually to aid in establishing effective preventive measures and treatment guidelines in Korea.