Abstract: The present research aims at investigating the changes in the blood sugar of athletic students after taking part in certain aerobic sport activities. The idea behind this research is originated from the fact that many specialists in physiology believe that reduction of sugar in blood (hypoglicemy) or its increase (hyperglicemy) can cause irreparable or irretrievable damages in the body. Also, a lot of researches have shown the reduction of sugar in blood after physical activities. In this researches fifteen students have taken part and have gone through tests twice and 10cc of their blood has been taken for analysis. Since the observed t (3.72) related to changes in blood sugar before and after aeorbic physical activities is higher than the critical at p<= 0.05 level at the degree freedon of (N-1), the null hypothesis is rejected and the sport activity causes a statistically meaningful change in blood sugar. However, this change is not due reduction but a 9.92% increase. For the acceptance or rejection of the second hypothesis, the blood sugar level of the subject as one factor and their weights (by using certain criteria for height and weight) as the second factor were studied. The Pearson’s correlation coefficient was applied for statistical analysis. Since the correlation of 0.406 was obtained statistically, speaking a relative correlation between blood sugar of the subjects and their weights was ovserved.