This report presents systematic clinical data regarding psychiatric diagnoses, personal and family psychiatric histories, and symptomatologic aspects of 90 consecutive human immunodeficiency virus (HIV)-seropositive and acquired immune deficiency syndrome (AIDS) patients, of whom slightly less than two thirds were at risk due to intravenous drug abuse. In addition, a comparison was made between the distribution patterns of these variables at various stages of HIV illness and related at-risk behaviors. Eighty-four percent of the patients met criteria for a spectrum of DSM-III-R diagnoses (mostly affective) that were associated with high rates of affective and alcohol abuse disorders among first-degree relatives. Mood disorders did not differ significantly between the two main groups at risk (intravenous drug users [IVDUs] v others) by gender, age, or stage of illness. The overall data from the rating scales show high levels of psychic and somatic anxiety in the early stages of illness, whereas cognitive symptoms, retardation, and disorientation are dominant in later stages. A noteworthy finding in this study is that many depressed patients demonstrated current and/or past hypomanic, hyperthymic, or cyclothymic features with no evidence of brain damage detectable by computed axial tomography (CAT). These temperamental attributes, which preceded HIV infection, may have served as risk factors for both drug abuse and impulsive sexual behavior in all types of at-risk groups.