Pneumonia is still a complication leading to high morbidity and mortality rates in acute leukemia (AL) patients. To evaluate the incidence, risk factors and outcome of pneumonia in a single institution we retrospectively studied 288 patients observed between 1994 and 2000, affected by AL (218 acute myeloblastic leukemia and 70 acute lymphoblastic leukemia [ALL]) treated with an anthracycline-containing induction regimen. Of 288 patients, 80 (27.7%) developed pneumonia: 67/80 had acute myelogenous leukemia (AML) and 13/80 had ALL. At univariate analysis only advanced age correlated with the risk of pneumonia (P < 0.001). Of the 80 pneumonia cases, 25 (31.2%) were microbiologically documented and 65 (68.8%) were clinically demonstrated; pneumonia responded to treatment in 44/80 (55%) patients; among the patients with positive outcome of their pneumonia 33/44 (75%) achieved complete remission whereas only 2/36 (5%) patients with a negative outcome achieved complete remission. At multivariate analysis the determinants of positive outcome of pneumonia were younger age (P < 0.05), the achievement of complete remission (P < 0.005) and the recovery of neutrophils (P < 0.005).