We studied the distribution of HLA-DP antigens in 74 HIV-infected Danish homosexual men and 188 ethnically matched healthy individuals, using the primed lymphocyte typing (PLT) technique. Forty of the patients developed AIDS within 3 years after diagnosis, whereas the remaining 34 were healthy or had only minor symptoms for 3 years or more (median observation time was 42 months). HLA-DPwl seemed to be decreased (relative risk = 0.3) in AIDS patients (5.0 per cent) when compared to patients with minor symptoms (14.7 per cent) and healthy controls (14.9 per cent). These differences were, however, not statistically significant. There were no other apparent deviations between patients (or subgroups of patients) and controls.