Purpose: On the other hand, fatigue is one of the most important indicators of aging syndrome. This study aimed to investigate the relationship between the level of physical activity and fatigue in elderly residents of rest homes in Tehran. Method: This was a descriptive correlational study in which 20 rest homes located in Tehran province constituted the study population. By visiting rest homes, the eligible subjects were chosen. Physical activity was measured by the Physical Activity Scale for the Elderly (PASE). The FACIT Fatigue Scale is a short, 13-item, easy to administer tool that measures an individual’s level of fatigue during their usual daily activities over the past week. Nutritional status was evaluated by mini nutritional assessment (MNA). Results: The results of statistical analysis indicated a significant and positive correlation between PASE and FACIT scores (r=0.48, p<0.01) while, there was a significant negative correlation between FACIT score and age (r=-0.23, p<0.01). Also, there was a significant positive correlation between MNA and FACIT (r=0.40, p<0.01). In addition, a significant positive correlation was found between MNA and PASE score (r=0.31, p<0.01). Conclusions: The findings of this study indicate that holding sports classes under the supervision of exercise physiologists is an essential matter to increase health and prevent age-related complications in elderly residents of Tehran rest homes.