Background: aging is associated with an increase in vascular dysfunction but it can be prevented by exercise training. However, the effect of circuit resistance training as a useful training method in improving cardio-respiratory and muscular strength is unclear. Objectives: The aim of this study was to investigate the effect of CRT on plasma endothelin-1, nitric oxide (NO) and vascular size in aged men. Methods: Twenty healthy aged men (55 ± 5 year) were randomly divided into control and CRT groups. CRT group performed circuit resistance training with 40 - 60 one repetition maximum for twelve weeks (3 times per week). Vascular size, plasma endothelin-1 and NO, blood pressure and heart rate were measured forty eight hours before and after the training period. Results: CRT increased the vascular size and decreased endothelin-1 and systolic blood pressure compared to the pre-test; however, it had no effect on NO concentration and heart rate. In comparison with the control group, CRT significantly increased the vascular size and decreased endothelin-1 and blood pressure but there was no significant difference in NO concentration and heart rate between the two groups. Conclusions: Circuit resistance training as a proper training method could induce the increase in endothelial function in aged individual and prevents vascular dysfunction related to aging.