Mesenchymal stem cells from cord blood (CB) are actively used for the correction of cardiovascular disorders, the important role in the formation of which belongs to chymase and tonin (or kallikrein II), capable of forming angiotensin II in humans. In elderly people, the action of tonin leads to an increase in blood pressure and heart rate against the background of chymase activity decrease. The aim of our work was to investigate the activity of chymase and tonin under allogenic CB injection to old rats with stress-induced hypertension (SIH). The SIH was modeled using the “non-avoidance” test, conducting one session daily for three weeks until stable hypertension was achieved. Allogeneic cryopreserved CB, which was obtained from 17-19-day-old rat embryos, was injected intraperitoneally once in 0.5 ml (3.5∙107 cells/ml). 4 days after the injection, the activity of chymase and tonin was determined by enzymatic methods in blood serum, nuclear-free homogenates of brain cortex, lung, heart, liver, and kidney tissues. The SIH development led to a decrease in the chymase activity, more significantly in blood serum, brain cortex, kidneys and the tonin activity in the brain cortex, heart and kidneys. After the CB injection to rats with SIH, the chymase and tonin activities increased in all samples except the liver. Significant changes were noted only for tonin in the brain cortex and kidneys. At the same time, normalization of this indicator was not observed in the brain cortex, which indicates the need to increase the dose of the cellular drug or the number of injections and prolong the observation period to achieve a full renewing effect. Thus, allogeneic umbilical CB injection to 24-month-old rats with SIH leads to restoration of chymase and tonin activity in most of the studied tissues.