Depression is found frequently with HIV/AIDS, but the reasons for this association are unclear. An important question is the possible effect of immunological factors on depression. In 201 persons with HIV/AIDS being seen in clinics in Uganda a study was mounted to address this issue. Information on depression was collected, and the diagnosis of major depressive disorder (MDD) was based on DSM-IV criteria. The frequency of MDD was 30.8% in this population.