A retrospective study of 55 HIV-1 seropositive African patients living in the UK, seen between January 1986 and November 1993, showed a total of 26 (47%) patients with AIDS. Thirty-one (56%) had symptomatic HIV disease at the time of presentation of whom 19 (34.5%) had an AIDS defining condition. Tuberculosis was the most common AIDS defining illness, accounting for 27% of all initial AIDS diagnoses, followed by by Pneumocystis carinii pneumonia and oesophageal candidiasis in 19% each and chronic mucocutaneous genital herpes in 15%. The mean CD4 count at the time of the first AIDS defining event was 91 x 10/mm3 (range 4-320 x 10/mm3). The profile of AIDS defining illnesses was different to published data of homosexual men and injecting drug users in the UK. This has practical implications when considering differential diagnoses and screening as well as prophylaxis for opportunistic infections in this group of patients.