The sex differences of age-related changes in the functional activity and expression of receptor and regulatory proteins of the renin–angiotensin system (RAS) in the aorta and myocardium of rats is evaluated. It was found that, with age in females, the sensitivity of the aorta to the vasoconstriction action of angiotensin II increases, while in older males it remains unchanged. In the aorta of old females, a decrease in the mRNA levels of ACE, MasR, and ACE2 was revealed by 1.6, 1.8, and 4.4 times, respectively. It has been shown that during aging in the left ventricle of females, the level of MasR and ACE2 mRNA decreases; in males, on the contrary, the level of ACE and MasR mRNA increases. The results obtained indicate the sexual characteristics of age-related changes in RAS activity in the vessels and heart of rats. [ABSTRACT FROM AUTHOR]