Objectives: To study the characteristics of bone marrow histology in patients with Myelodysplastic syndrome (MDS) at BachMai Hospital. Patients and Method: Study on bone marrow histology in 112 patients diagnosed MDS according to WHO-2001 from January 2009 to October 2011. Results: Patients mainly in the elderly, the average age is 58.7. Disease in both sexes, the percentage of male I female is 1,15. 45.5 percent of patients have bone marrow cell density increased. 42.0 percent of patients had normal marrow cells, and 12.5 percent of patients marrow cell density decreased. 96,4 percent patients had abnormal location of Hematopoietic cells. 44,6 percent patients had Abnormal Location of limmature Precusor (ALlP). 75 percent of patients had proliferative fibrosis. Conclusion: There are changes in the bone marrow histology of patient with MOS.