We compared the results of clinical and experimental studies of endocrine parameters in patients with myocardial infarction and arterial hypertension and NISAG rats with hereditary stress-induced arterial hypertension during experimental myocardial infarction. Changes in the content of corticosterone, aldosterone, insulin, triiodothyronine, and thyroxin were similar in animals and patients with myocardial infarction and arterial hypertension. The disadaptive course of myocardial infarction against the background of arterial hypertension can be explained by reduced compensatory capacity of the myocardium.