The ICU records of 31 patients with the acquired immunodeficiency syndrome were reviewed. Of 23 (74%) patients admitted for respiratory failure requiring intubation and mechanical ventilation, 20 (87%) patients had Pneumocystis carinii and/or cytomegalovirus pneumonia. Of the eight patients admitted without respiratory failure, five (63%) were monitored after brain biopsy. Respiratory failure patients remained in the ICU for 10 +/- 1 days, compared to 5 +/- 1 days for those without respiratory failure (p less than .05). Overall mortality was 24 patients (77%); 21 (91%) of 23 respiratory failure patients died, compared to three (38%) of the eight without respiratory failure (p less than .01). All seven ICU survivors lived to hospital discharge.