One hundred forty-five patients were initially seen with Pneumocystis carinii pneumonia (PCP). Of the many features examined, several variables were identified early in the hospitalization for PCP that were associated with poor survival. These included multiple admissions, leukocytoses, elevated serum lactate dehydrogenase levels, decreased arterial oxygen pressure (tension), decreased arterial carbon dioxide pressure (tension), and decreased serum albumin levels. Variables that were associated with increased survival included normal respiratory rates and normal findings on lung examination. Patients with multiple pulmonary infections displayed higher mortality rates than patients who had only PCP. Finally, our data did not suggest that the degree of immunosuppression affected in-hospital mortality for PCP.