This study prospectively assessed the impact of treatment modality, virus load, and CD4 cell count of <50 cells/mm(3) on human immunodeficiency virus disease progression. The incidence rate of new AIDS disease or death was 54.8 (95% confidence interval, 48.7-59.9) per 100 person-years of follow-up. Independent predictors related to progression were latest CD4 cell count (relative risk [RR], 0.84/10 mm(3) higher; P<.0001), latest hemoglobin level (RR, 0.79/g/L higher; P<.0001), Pneumocystis carinii pneumonia prophylaxis (RR, 0.49; P<.0001), latest body mass index (RR, 0.93/kg/m(2) higher; P=.002), latest virus load (RR, 1.11/log(10) higher; P=.03), and intensity of treatment (RR, 1.82, P=.004; RR 2.27, P<.0001; RR 2.46, P=.0001; RR 2.33 P<.0006; 5.10, P<.0001, respectively, for 4, 3, 2, 1, or no drugs vs. >or=5 drugs). Although reverse causality cannot be excluded, more intense antiviral treatment appears to decrease the risk of progression in immunocompromised patients.