hematological parameters in young, active males. Material and Methods: 26 male, university students without any previous smoking experiences or regular exercise programs (age, 19/23 1/07 years and BMI, 22/53 5 kg/m2) were randomly selected and divided into two groups: control and exercise. The exercise group (13 students) did an 8-week aerobic training three times a week with the intensity of 55% to 75% of maximum heart rate but the control group just (13 students) did their everyday activities. Blood samples were collected before the first session of aerobic training and after the last session, at a specific time (7:00 a.m.) from both control and exercise group. The second blood samples were collected after the heart rate of the exercise group returned to its resting values and were used to examine the following parameters: clotting and bleeding times, amount of fibrinogen, hemoglobin, hematocrit and number of red and white blood cells and platelets. A timer, a fibrinogen kit and a cell counter were used in this phase. Student t-test and paired T-test were run to analyze the obtained results. The significance level was set at P= 0.05. Results: The findings showed that during an 8 – week morning exercise the number of red blood cells, hemoglobin levels, and hemotocrit percentage increased. Fibrinogen levels and prothrombin formation time have also increased significantly (P≤0.05), while the bleeding times and the number of platelets decreased significantly. Discussion and Conclusion: The findings of this study reveal that an eight – week morning aerobic training does not have any negative effect on hematological parameters of young , active males with healthy metabolic, kidney and cardiorespriatory systems
