Abstract: The bone marrow Cell Cycles in 8 patients with iron deficiency anemia （IDA）, 8 with aplastic anemia （AA） and 12 with myelodysplastic syndrome （MDS-RA, RAS） were analysed with flow cytometry. The percentages of proliferative cells （S+GaM） were similar in normal controls, patients with IDA, RA and RAS, while they were much lower in patients with AA, and there was a significant difference as compared with that in the control group （P＜0.05）. The biological signieigace of this assay was discussed in the paper.