A 69-year-old woman was admitted with sudden chest pain and high fever. Electrocardiography showed negative T waves in the precordial leads. Subsequently, pleural and pericardial effusion developed, but the symptoms and signs subsided without specific therapy. On day 31, fever, left shoulder pain and pleural effusion reappeared. 67Ga scintigraphy showed abnormal uptake in the chest and left shoulder. Blasts were detected in the peripheral blood on day 44, and in the pleural effusion and bone marrow on day 45. The blasts were positive for Philadelphia chromosome, CD10, CD19, CD33, CD34 and IgH-chain rearrangement and negative for myeloperoxidase. The clinical picture of the preceding pleuropericarditis was that of viral or idiopathic origin, but its relationship with acute lymphoblastic leukemia was unclear. Inflammatory chemokines in the pleural space may have induced invasion of the leukemic cells.