Introduction: The Physiological effects of fasting on athletes have been of an interest to some researchers and different results have also been obtained. In some researches, the effects of Weight training and practice in heat on blood factors, fluids and electrolytes were investigated and it was found that the plasma volume was reduced and the concentration of blood and electrolytes were increased. The purpose of this research was to study and compare the effects of Weight training on hematological factors among the students of Physical Education in fasting and non- fasting conditions.Materials and Methods: This study is a semi-experimental research. The population of the study includes male physical education students of Islamic Azad University of Mashhad. Having voluntarily completed the initial questionnaire, 15 of the participants were randomly chosen as the statistical sample. Recued tests were taken twice: three days before Ramadan and in the fourth week of Ramadan (before and after the exercise sessions).The training protocol included a session of Weight training (circuit training). The exercise intensity, time of training and temperature were controlled prior to the exercise sessions. Data analysis was done by using one variable analysis of variance (F test at the alpha level of 5%.Results: A) Ramadan fasting had no significant effect on the subjects’ body Weight, fasting blood sugar, hemoglobin, hematocrit, red blood cells, platelets and white blood cells. B) Training had significant effect on the subjects’ body Weight, hemoglobin, hematocrit, red blood cells, platelets and white blood cells, but had no significant effect on their blood sugar. C) Fasting and training have significant interaction effects on the subjects’ Weight, blood sugar, platelets and white blood cells and had no significant effect on the subjects’ hemoglobin, hematocrit and red blood cells.Conclusion: Training in fasting condition could probably cause some changes in hematological factors due to the reduction of body water, but changes in blood sugar are more obvious.Therefore, to prevent reducing the rate of blood sugar, it is recommended that the intensity of training be less than usual in fasting condition.