OBJECTIVE Pulmonary infection is a frequent cause of morbidity and mortality in patients with acquired immunodeficiency syndrome (AIDS), and Pneumocystis carinii pneumonia (PCP) is the predominant infection in these patients. In those patients who experience progression to respiratory failure from PCP, the reported mortality rate has been between 87% to 100%. This, in addition to the ultimately fatal outcome of patients with AIDS, has led many physicians to question the advisability of instituting mechanical support for respiratory failure in the setting of PCP. It had been our impression that the outcome of patients on our service was not as poor as was generally reported. We therefore undertook a retrospective analysis of our clinical experience. METHODS We reviewed the clinical course of patients admitted to our service between December 1984 and June 1988 who required intubation and mechanical ventilation for PCP or presumed PCP. RESULTS Thirty-three cases were identified with 18 survivors (54.5%) and 15 non-survivors (45.5%). Twenty-five of the 33 patients were intubated for their first episode of PCP, with 16 survivors (64%), whereas the remaining eight patients were intubated for their second episode of PCP, with two survivors (25%). We were not able to identify any parameters that predicted survival, although the serum lactate dehydrogenase level was useful in following the response to treatment. CONCLUSIONS It is our belief that there is a reasonable chance of survival for patients requiring mechanical ventilation for PCP. We question the wisdom of avoiding intubation and mechanical ventilation altogether in patients with PCP due to the presumption of fatality in this clinical situation.