Fifty-five episodes of Pneumocystis carinii pneumonia (PCP) in AIDS patients were evaluated to assess clinical and laboratory risk factors predicting the probability of surviving the acute episode of PCP and the long-term survival after PCP. Age > 45 yrs, PaO2 < 50 mmHg, AaPO2 > 50 mmHg, and LDH > 800 IU/L correlated strongly with early mortality; patients who needed mechanical ventilation had a significantly lower PaO2 and serum albumin, and higher AaPO2 and LDH compared to the patients who did not. Neither age nor PaO2, AaPO2, LDH, albumin, days from onset, time for recovery, CD4+ cell count correlated with long-term survival of AIDS patients with PCP. Informations obtained at initial presentation of PCP may predict early outcome and influence therapeutic approach, improving chances for survival.