Urinary excretion of norepinephrine and epinephrine was measured in 30 patients with myocardial infarction for five days after admission to a cardiac care unit. Patients with uncomplicated hospital courses or those with primary ventricular fibrillation or complete atrioventricular block showed a similar pattern, ie, high initial levels with a slope to normal range over the five-day period. Patients with multiple complications, particularly of a hemodynamic nature, showed lower initial levels and a different slope over the five-day period. Some instances of catechol elevation at time of psychological stress are presented.