The purpose of present study was to investigate the effect of the exercise on elastic characteristics of the aorta in spontaneously hypertensive rats (SHR). SHR and Wistar control rats (WCR) of both sexes were used in this study. Male and female SHR were respectively divided into two groups (exercised; Ex and non-exercised; nE) at 6 weeks of age: SHREx (male), SHRnE (male), SHREx (female) and SHRnE (female). Exercised SHR were placed in cages with rotating wheels capable of voluntary running. After 24 weeks of feeding, values of pulse wave velocity (PWV) were measured on aortas. The results were as follows: 1) Body weights of male SHREx were lower than those of male SHRnE; whereas female SHREx were heavier than female SHRnE. Food comsumptions of SHREx groups tended to be more than those of SHRnE groups. 2) Female SHREx showed greater running activity than male SHREx. There was no constant difference in systolic blood pressure obtained by an indirect tail-cuff method between SHREx and SHRnE in both sexes. 3) PWV values of male SHREx were significantly lower than those of male SHRnE. In the females, there was no difference between SHREx and SHRnE. 4) Media thickness rates (v.s. diameter) of thoracic aortas of SHREx were significantly lower than those of SHRnE in both sexes. These results suggest that voluntary exercise is effective to improve elastic characteristics of the aorta especially in male SHR.