Dasatinib has been associated with an increased risk of bleeding, with the most prominent risk noted in patients with advanced-stage chronic myeloid leukemia and thrombocytopenia. We herein report two cases of Philadelphia chromosome-positive acute lymphoblastic leukemia in which a subdural hematoma developed in association with low-dose (40-50 mg/day) dasatinib treatment and lumbar puncture for intrathecal methotrexate injection. Both patients were in complete remission, with normal platelet counts and coagulation status. We suggest that dasatinib, even at a low dose, may impair platelet aggregation and that lumbar puncture may increase the risk of a subdural hematoma (occasionally bilateral) in patients receiving dasatinib.