Human Immunodeficiency Virus (HIV) related Pneumocystis carinii pneumonia (PCP) associated with severe respiratory failure is an increasingly common problem in major centres and is associated with a high mortality in previous and recent studies. Early in the epidemic, alternatives to invasive intensive care treatment were utilized in our institution and found to be successful. When respiratory failure developed, mask CPAP was used instead of intubation and ventilation. A retrospective review of 175 cases of HIV infected patients with confirmed first presentation PCP was undertaken. Treatment with our protocol resulted in an overall hospital mortality of 9%. Those patients who did not require supplemental oxygen or respiratory support had no in-hospital mortality. The group who required supplemental oxygen had a mortality of 10%. If respiratory failure supervened (severe respiratory distress, PaO2 less than 50 mmHg, SaO2 less than 90% on mask oxygen), CPAP was introduced. The mortality in this group was 22%. Only two patients were admitted to the intensive care unit for respiratory support after failure of CPAP. Both patients were intubated and received intermittent positive pressure ventilation (IPPV). Both patients died.