Introduction: Heart secretes hormones such as natriuretic peptide. The purpose of this study was to investigate the effects of 12 weeks of resistance training on these hormones. Methods: Twenty four healthy men (Mean age ± SD: 24.9 ± 3.2 years) were randomly allocated to experimental and control groups. Subjects in the experimental group performed a 12-week resistance training program, 3 sessions per week at an intensity between 55 to 75% of maximum strength. Each session of training included three sets of 10 repetitions for 8 exercises of upper and lower body. Two blood samples were taken before and 48 hours after training period for measuring ANP, BNP, endothelin-1 and angiotensin II. Results: Resting values of ANP before and after 12 weeks of training for experimental group were 0.87±0.22 and 0.89±0.30 nmol/L, respectively, while these values for control group were 0.92±0.30 and 0.92±0.31 nmol/L, respectively. Data analysis revealed no significant difference between the effects of training on resting levels of ANP, BNP, endothelin-1 and angiotensin II in two groups (P>0.05). In addition, no significant difference between pre- and post-training values of ANP and BNP was observed when data were separately compared in each group. Conclusion: Based on the findings of the present study, it could be concluded that resistance training does not induce changes in resting levels of cardiac hormones (ANP and BNP), and that beneficial changes induced by exercise training might not be due to changes in these parameters.