Pleural effusions are rarely observed in patients with acute myelogenous leukemia (AML), acute lymphocytic leukemia (ALL) and myelodysplastic syndrome (MDS)/myeloproliferative neoplasm (MPN). Therefore the underlying etiology of pleural effusions and the efficacy and safety of pleural procedures in this population has not been well studied. In a retrospective review of cases from 1997 to 2007, we identified 111 patients with acute leukemia or MDS/MPN who underwent pleural procedures. Clinical characteristics were reviewed, and survival outcomes were estimated by Kaplan-Meier methods. A total of 270 pleural procedures were performed in 111 patients (69 AML, 27 ALL, 15 MDS/MPN). The main indications for pleural procedures were possible infection (49%) and respiratory symptoms (48%), and concomitant clinical symptoms included fever (34%), dyspnea (74%), chest pain (24%) and cough (37%). Most patients had active disease (61%). The most frequent etiology of pleural effusions was infection (47%), followed by malignancy (36%). Severe thrombocytopenia (platelet count < 20 × 10(3)/µL) was present in 43% of the procedures, yet the procedural complication rate was only 1.9%. Multivariate analysis revealed that older age, AML, MDS/MPN and active disease status were associated with a shorter median overall survival. Infection and malignant involvement are the most common causes of pleural effusion in patients with acute leukemia or MDS. After optimizing platelet count and coagulopathy, thoracentesis may be performed safely and with high diagnostic yield in this population. Survival in these patients is determined by the response to treatment of the hematologic malignancy.