Here, we assessed the histological changes in myocardial structure in old rats against the background of persistent arterial hypertension. This study was aimed to investigate the structural organization of tissues and vessels of animal myocardium to days 3, 7 and 30 after development of stress-induced arterial hypertension. The experiments were performed in 28-30-month-old white outbred male rats. The pathological state was simulated according to the patented technique under specialized cage conditions with a combined impact of stimuli (light, sound, electricity). Histological and histochemical assessments of the myocardium within these research terms showed the development of destructive and dystrophic disorders in myocardial tissues and vessels, the progression of interstitial and perivascular oedema, the occurrence of diapedetic hemorrhages. Significant differences in morphological structure of the myocardium in hypertensive old rats as compared with the control normotensive animals were established. These findings make it possible to clarify the pathogenesis of the stress-induced arterial hypertension development, which is a key element in designing the current anti-stress and antihypertensive therapy.