To evaluate the function and effectiveness of a multidisciplinary team for managing human immunodeficiency virus (HIV) infection, we conducted a follow-up cohort study of HIV-positive patients managed according to a clinical care path at a staff-based health maintenance organization (HMO). The study group consisted of 230 HIV-positive health plan members who received care at the Kaiser Permanente Santa Rosa medical center (KPMC-SRO). In 1994, the comparison group consisted of 4747 HIV-positive health plan members who received care at Kaiser Permanente’s 18 other medical centers in northern California. The percentages of acquired immunodeficiency syndrome (AIDS) and HIV-positive patients as determined by CD4+ T-cell counts were similar (P = 0.97). Compared with patients at the other Kaiser Permanente medical centers, KPMC-SRO patients had more visits with nurse practitioners (rate ratio [RR] = 1.72) and nutritionists (RR = 12.3) and fewer visits with primary care physicians (RR = 0.82). More HIV-positive members at KPMC-SRO received social workers’ services (27% at KPMC-SRO vs 6% for patients at the other Kaiser Permanente medical centers) and fewer used emergency services (RR = 0.92) and psychiatric services (RR = .89). At KPMC-SRO, the mean number of days that AIDS patients spent in the hospital decreased from 7.8 (1991) to 2.01 (1994). Hospital admissions were fewer (AIDS patients, RR = 0.67; HIV-positive patients without AIDS, RR = 0.45), and length of stay was briefer, compared with patients at the other Kaiser Permanente Medical Centers. The mean cost of HIV-related drugs for patients seen at KPMC-SRO ($2343 per infected member) was lower than that for patients seen elsewhere in the region ($3289 per infected member). These results suggest that in an HMO setting, managed care provided by a dedicated interdisciplinary team according to a clinical care path can substantially and favorably affect resource use.