Respiratory failure due to Pneumocystis carinii pneumonia (PCP) is the most common complication requiring an intensive care unit (ICU) for persons with AIDS. In this study, we evaluated patterns of ICU use for ICU patients with first-episode PCP in 15 Veterans Administration Medical Centers from 1987 to 1991. Twelve percent of all patients with PCP received care in the ICU. The survival rates improved steadily during these years. Although there was little variation in the relative frequency of ICU use, the effectiveness of ICU use appeared to improve over time. In the more recent years, relatively more survivors and relatively fewer nonsurvivors received care in an ICU. Changes in medical practice such as adjunctive use of steroids for severe cases of PCP and more effective use of scarce resources may account for the improved survival rates for patients with PCP who are treated in an ICU.