To determine whether the outcome of intensive care for patients with AIDS, Pneumocystis carinii pneumonia (PCP), and respiratory failure has changed, we studied patients admitted to the intensive care units an San Francisco General Hospital from 1981 to 1988. We compared the course of patients with PCP and respiratory failure admitted to the intensive care unit from 1986 to 1988 with a similar cohort hospitalized from 1981 to 1985. The hospital survival rate for the 35 patients in the 1986 to 1988 cohort was 40%, compared with 14% for the 42 patients in the 1981 to 1985 cohort (p less than 0.01). Age, episode of PCP, time since AIDS diagnosis, anti-PCP therapy, and important clinical variables were similar in both cohorts. Corticosteroids were used commonly in the recent era. Patients who received steroids had an in-hospital survival rate of 46%, compared with 22% for those who did not receive steroids (p = NS). In a stepwise logistic regression model, ICU care in the recent era and higher serum albumin at the time of ICU admission were the only variables significantly associated with survival. The hospital survival of patients with PCP and respiratory failure has improved. The improvement could not be explained by patient selection or by better anti-PCP therapy. The apparent beneficial effect of corticosteroids deserves further study. The improvement in ICU outcome was reflected in increased ICU utilization by patients with AIDS, PCP, and respiratory failure.