Myelodysplastic syndrome is a bone marrow failure in which differentiation and maturity do not happen naturally and dysplasia exists in each of 3 cell categories in Bone marrow. Refractory anemia is one of the major complaints with which the patients come to hematology clinics, which in diagnostic considerations lead to MDS as diagnosis. Often there is no recognized reason for this, so it is called "primary MDS". In practice, we meet some patients who have MDS criteria however we can also find specific reasons for it; therefore we call it "secondary MDS". One of the most important reasons for secondary MDS is the side effects of medications used in chemotherapy and radiotherapy in patients who undergo these therapies. We observed 6 patients in this case study during lengthy follow up that were diagnosed as MDS and during follow up period malignancy appeared in 6 cases. Supportive and therapeutic measures in these patients did not considerably improve blood cell count, most patients required blood injection and antibiotics for infection treatment. However align with malignancy treatment such problems are completely resolved both in terms of clinical and laboratory.