In the early 1990s, hospital survival among patients with human immunodeficiency virus (HIV)-related Pneumocystis carinii pneumonia (PCP) and respiratory failure was poor, approximately 20%. We examined ICU use and outcomes for patients with acute respiratory failure from PCP from 1995 to 1997. We conducted a retrospective medical record review using a random sample of 71 hospitals in seven regions of the United States. Among 1,660 patients with confirmed or presumed PCP, 155 (9%) received mechanical ventilation for respiratory failure. Factors that predicted use of mechanical ventilation, independent of severity of illness on hospital admission, included African-American ethnicity and geographic location (p </= 0.002). Hospital survival for patients receiving mechanical ventilation was 38% (95% CI 30, 46). Controlling for severity of illness, patients who were on PCP prophylaxis prior to developing PCP were less likely to survive to hospital discharge (p </= 0.02). There were no significant differences in hospital survival regardless of whether patients had received less than or more than 5 d of PCP treatment prior to respiratory failure (39 versus 29%; p = 0.5). In conclusion, from 1995 to 1997, hospital survival after PCP requiring mechanical ventilation was approximately 40%. Physicians caring for patients with severe HIV-related PCP should be aware of the improvements in outcomes for this disease before making recommendations about withholding or withdrawing ventilatory support for respiratory failure.