The authors examined the concentrations of zinc, HGH, insulin and glucose in blood serum of 40 patients with acute myocardial infarction. Zinc and HGH concentrations in blood serum correlated well with changes in the clinical state in these patients. The more severe the condition of the patient, the greater zinc concentration fall and HGH concentration rise in blood serum were noted. All the changes were statistically significant (P less than 0.001) in cases of severe clinical course and most distinct in cardiogenic shock. On the other hand, in MI of mild course, zinc concentration fall in blood serum was not accompanied by HGH rise. A positive correlation between the concentrations of zinc and HGH found in normal subjects became negative in patients with acute MI of severe course. The changes of zinc and HGH concentrations seem to be due to the non-specific effect of acute myocardial stress, particularly enhanced in MI with severe course and cardiogenic shock, Observation of the intensity of changes may have prognostic significance due to the fact that they were most distinctive in MI of most severe course.