Background and Purpose. Cancer metastasis to bone marrow (BM) is universal-ly a poor prognostic feature. Awareness of BM metastasis by simple blood test and confirmedby BM examination is crucial to improve treatment outcome. The aim of this study was to investigate the hematologic manifestation of adult patients with cancer BM metastases di-agnosed by BM aspiration. Methods. Retrospective review of 1330 BM aspirations carried out in Cathay General Hospital between March 2007 and December 2014. Patients with pres-ence of cancer BM metastasis were the study group. Patients with normal appearance of BM were the control group. Basic clinical characteristics, complete blood counts and survival of patients were obtained from the hospital records. Results. Twenty-nine patients (2.2%) had evidence of cancer BM metastasis. Breast cancer (34.5%) and colorectal cancer (17.2%) were the most common cancers associated with BM metastasis. As compare with the control group, BM metastasis patients had more cases of anemia (100% vs. 74.9%), thrombocytope-nia (82.8% vs. 24.6%), leukoerythroblastosis (69% vs. 2.2%) and high lactate dehydrogenase (LDH) (90% vs. 38.2%). The most common site of metastasis other than BM was bone (n=25, 86.2%). Median survival after BM metastasis was 1.9 months and 6-month survival rate was 21.4%. Patients who received chemotherapy after BM metastasis had significantbetter sur-vival with medium survival of 5.4 months vs. 0.7 months. Conclusion. BM metastasis by cancer carries a poor prognosis. Anemia, thrombocytopenia, leukoerythroblastosis and high LDH suggest of possible BM metastasis. BM examination provides a quick way to detect metastasis. Patients who received chemotherapy had better survival.