Abstarct: Resistance exercise combined with proper nutrition intake can increase fat loss ratio during weight loss. The purpose of this study was to determine the effect of eight weeks of resistance training and a low calorie diet on body composition and serum levels of vitamin D in postmenopausal women. After calls, 22 postmenopausal women selected targeted and were included in two groups (12 person empirical group and 10 person control group) randomly. Empirical group exercised for 8 weeks and 2 days per week with 20-30% 1RM intensity. The control group members continued their usual physical activity over the course of 2 months. Serum levels of vitamin D and PTH in fasting state and body composition before and after the training course were evaluated with Inbody. hour diet recall 24 was used to evaluate the diet of empirical group. To analysis the data the analysis of variance statistical method was used. For tests significant level of P≤ 0.5 was considered. The results showed that after eight weeks of resistance training and low calorie diet, fat mass, fat percentage and BMI significantly reduced in the empirical group compared to control group while no significant change in other variables related to body composition and serum levels of vitamin D was not observed in postmenopausal women. Resistance training along with a low calorie diet prevent the loss of pure body mass and serum levels of vitamin D.