A pilot study was conducted with the aim of measuring the acceptability of voluntary testing for human immunodeficiency virus (HIV) antibody among patients attending sexually transmissible disease (STD) clinics. Three STD clinics, two public and one private, participated in the study which was conducted over a three-month period beginning in November 1988. For each patient attending the clinics, sex, date of birth, HIV transmission category and previous HIV test result were recorded. Patients who did not request the HIV antibody test were offered testing. Of the 2356 patients who were included in the analyses, 784 (34%) requested testing. For almost all patients (97%) who requested testing, a serum sample was collected and testing completed. Approximately half (55%) of those patients who were offered the test accepted testing. Overall, 70% of patients completed HIV antibody testing. Of the major transmission categories, the acceptance rate for those offered the test was lowest among homosexual men (45%), who also had the highest rate of HIV antibody seropositivity (11%) among those tested. Of patients who reported themselves to be HIV antibody seronegative prior to the pilot study, 78% were retested during the study and seven had a positive test for HIV antibody. We conclude that voluntary HIV antibody testing is acceptable in both public and private STD clinic settings, although a substantial amount of additional resources would need to be allocated to counselling if voluntary testing is to be introduced on a routine basis.