A 22-year-old male with Ph-positive chronic myelogenous leukemia (CML) was started on treatment with imatinib. After 12 months of therapy, he achieved a complete cytogenetic response (CCyR). Although the CCyR persisted in his bone marrow, he developed an isolated CML blast crisis in his central nervous system (CNS) after 29 months of therapy. He underwent allogeneic hematopoietic stem cell transplantation (HSCT) following combination therapy with dasatinib, intrathecal chemotherapy and cranial irradiation. Subsequently, 168 days after allogeneic HSCT, he was started on dasatinib maintenance therapy to prevent a CNS relapse. Thirty-eight months after allogeneic HSCT, he has sustained a complete molecular response in both bone marrow and CNS. We believe dasatinib has the potential to prevent CNS relapse if used for maintenance therapy after allogeneic HSCT.