The hematological effects of oral supplementation of zinc to training athletes are reported in the present study. A total of 30 subjects between 16 and 22 yr of age volunteered to participate in a 4-wk study. They were equally divided into three groups. Group 1 acted as resting controls receiving daily doses of 3 mg Zn/kg body wt. Group 2 was actively engaged in wrestling and exercised for 90-120 min, 5 d a week. Group 3 was also actively engaged in wrestling and exercised for 90-120 min, 5 d a week, but they were supplemented with 3 mg Zn/kg body wt per day. The erythrocyte, leukocyte, and thrombocyte counts and the hemoglobin values of all subjects participating in the study were measured before and after exercise at the beginning and at the end of the 4-wk study period. In all groups, there were no significant differences in the measured parameters before and after exercise. At the end of the supplementation period, the parameters of the subjects in groups 1 and 3 were significantly higher than those of group 2, both before (p<0.005) and after (p<0.05) exercise. These results suggest that zinc supplementation has a positive effect on hematological parameters in athletes.