We evaluated the effects of koumiss on some hematological and biochemical characteristics of persons who exercise. Eighteen sedentary males were assigned to three equal groups: koumiss (K), koumiss + exercise (KE) and exercise alone (E). Leukocytes (WBC), differential leucocyte count, erythrocytes (RBC), hemoglobin (HGB), hematocrit (HCT), platelet (PLT), glucose, total cholesterol, triglycerides, high density lipoprotein (HDL), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were assessed In blood samples. By the end of the study, triglycerides (TG) and cholesterol levels tended to decrease in all groups, but the decrease was significant only at day 15 for the KE group. HDL tended to be increased in all groups at day 15, but the increase was significant only in the KE group. We found that koumiss had beneficial effects on some hematological and biochemical characteristics.