Abstract: Objective To investigate the effect of hydroxamate (HDX, inhibitor of endogenous sulfur dioxide production) on blood pressure and vascular structure in rat. Methods 4-week-old SHRs (spontaneously hypertensive rats) and WKY (Wistar-Kyoto) rats were divided into control and HDX-treated group (respectively, n = 8). Five weeks later, the blood pressure, SO2 content and GOT activity in serum and aorta, morphometric parameters, proliferative index (PI) and the expression of p-ERK were determined. Results Compared with WKY rats, the blood pressure, ratio of wall thickness to lumen radius, PI and the expression of p-ERK in aorta were increased, while the SO2 content and GOT activity in serum and aorta were decreased in WKY+HDX groups (P < 0.05 or P < 0.01). The SO2 content and GOT activity in serum and aorta of SHR were lower than WKY rat (P < 0.05 or P < 0.01). Conclusions Endogenous sulfur dioxide might play a pivotal role in maintaining normal pressure and vascular structure.