Leukemia is a malignancy caused by precursor cells of white blood cell. It is a malignant tumor of hematopoietic organs, characterized by the disorder of hematopoietic function due to the proliferation of immature bone marrow cells or lymphatic cells and by abnormal tissue infiltration of leukemic cells. The major signs of leukemia are caused by the failure of bone marrow function. As the number of red blood cells decreases, anemia is to appear. The number of white blood cells in leukemia is usually increased but immature white blood cells circulating the body has little defense ability, thus become susceptible to infection. 27 year-old female patient who was treated chemotherapy and bone marrow transplantation after diagnosed as chronic myelogenous leukemia(CML) was diagnosed as osteomyelitis in mandible after clinical and dental radiographic film examination. Because of the result of examination, the involved tooth of the patient was extracted accompanied by sequestrectomy and saucerization under general anesthesia. After the patient had long term medication of antibiotics, the lesion was healed. Therefore. author, et al. report this case with literature review.