In this study, we investigated the effects of moderate exercise on the erythrocyte blood parameters in patients receiving the treatment of allogeneic bone marrow transplant. 20 patients attended the study voluntarily during the period of allogeneic bone marrow transplant. The volunteers were divided into two groups (treatment and control group). The treatment group was given moderate exercise program five days a week for eight weeks under the supervision of a doctor in charge. Subjects in the control group did not participate in any exercise program. By using Siemens advia 2120 blood count device at Hematology Central Laboratory, erythrocyte (RBC; Red Blood Cell) blood cell analysis was done. In comparing groups statistically, two-way analysis of variance was used in iterative measurements. In comparing the groups according to the measurements within themselves, one-way analysis of variance was used in iterative measurements. According to results of our study, there is no significant difference in comparisons of the variables belonging to erythrocyte parameters between-groups when the group effect is thought as independent (p>0.05). After the exercise given to the control and treatment groups, when the effect of time was taken into consideration, a statistically significant difference occurred according to the result of the comparison of iterative measurements of the variables of RBC, HGB, HCT, MCV, MCHC, RDW and HDW. As a result, it was seen that exercises had a positive effect on erythrocyte blood parameters. It is thought that this effect arose from the exercise program.