In order to limit the spread of myocardial infarction, 56 patients with acute myocardial infarction, admitted to hospital within 10 hours from the attack, were for two days treated with continuous intravenous drip infusion of glucose-insulin-potassium mixture (GIP) (300 ml glucose, 50 U common insulin, 60 meqv potassium chloride at the rate of 1 ml/kg/hour). The control group was composed of 48 patients who received intravenous drip infusion of physiological saline, at the rate of 20 drops per minute, for the same duration of time. The findings revealed an increased in glucose and potassium levels and serum osmolarity, and a drop in free fatty acids. It is suggested that GIP infusion to patients with myocardial infarction has a favourable effect on the metabolism of ischemized myocardium via a series of changes it produces in carbohydrate and lipid metabolism and blood electrolytic composition.