We measured the neutrophil function of 6 patients with AIDS and Kaposi's sarcoma (KS); 22 patients with AIDS-related complex (ARC); and 28 healthy, heterosexual controls. Neutrophils from patients with ARC showed significantly less chemotaxis (P less than or equal to .025) than did those from patients with AIDS and KS or from controls. Serum from patients with AIDS and KS or with ARC significantly (P less than or equal to .05) inhibited chemotaxis of neutrophils from controls; heat treatment of the serum abolished this inhibitory effect. Bacterial killing by neutrophils from patients with AIDS and KS or with ARC was also significantly (P less than or equal to .05) less than for neutrophils from controls, as was neutrophil phagocytosis binding of Candida albicans (P less than or equal to .05). Expression of OKM1 antigen was increased in the patients studied. Enzyme degranulation, adherence, and aggregation were also examined. The defects found in neutrophil function are selective and may be important in the increased susceptibility of patients with human immunodeficiency virus infection to bacterial and fungal infections.