Abstract—Vascular senescence is closely associated with age-related vascular disorders and is enhanced by angiotensin (Ang) II type 1 receptor stimulation. However, the role of Ang II type 2 receptor activation in vascular senescence is still an enigma. Ang II stimulation significantly increased senescence-associated -galactosidase activity and the level of 8-hydroxy-2'-deoxyguanosine, with enhancement of oxidative stress and expression of Ki-ras2A, p53, and p21 in vascular smooth muscle cells (VSMCs) from wild-type (Agtr2⁺) mice, whereas these effects of Ang II were enhanced in VSMCs from Ang II type 2 receptor null (Agtr2^-) mice. Administration of an Ang II type 1 receptor blocker, valsartan, attenuated these parameters, with less effect in Agtr2^- VSMCs. Ang II stimulation increased methyl methanesulfonate sensitive 2 (MMS2) expression in Agtr2⁺ VSMCs but not in Agtr2^- VSMCs. MMS2 small-interfering RNA treatment enhanced Ang II–induced senescence-associated -galactosidase activity and 8-hydroxy-2'-deoxyguanosine level with no significant changes in oxidative stress markers and the expression of Ki-ras2A, p53, and p21. Moreover, exposure of Agtr2⁺ VSMCs to hydrogen peroxide and ultraviolet irradiation induced marked increases in senescence-associated -galactosidase activity and 8-hydroxy-2'-deoxyguanosine level, which were further enhanced in Agtr2^- and MMS2 small-interfering RNA–treated Agtr2⁺ VSMCs. Agtr2⁺ mice exposed to x-ray irradiation showed increases in senescence-associated -galactosidase activity and 8-hydroxy-2'-deoxyguanosine level in the aorta, which were further exaggerated in the aorta of Agtr2^- mice with a lower MMS2 level. These findings suggest that Ang II type 2 receptor signaling attenuates DNA damage and consequent vascular senescence at least in part through MMS2 transactivation and propose the beneficial effects of Ang II type 2 receptor stimulation with Ang II type 1 receptor blockers in age-related vascular disorders.