The encephalopathy associated with direct nervous system infection by the human immunodeficiency virus (HIV) has been recognized as one of the major debilitating aspects of the acquired immunodeficiency syndrome (AIDS) and of pre-AIDS conditions. A comprehensive neuropsychological examination of symptomatic HIV-infected subjects without opportunistic cerebral disease demonstrated a distinctive pattern of cognitive deficits marked by prominent attentional impairment. Evidence of organizational and reasoning impairments also was observed, but language, visual-spatial, and memory consolidation abilities were relatively preserved. The findings suggest a profile of impairment similar to other cognitive syndromes involving dysfunction of predominantly anterior brain structures and projections and suggest a rationale for psychostimulant drug treatment.