Twenty-two patients were studied during hospital admission for cardiac catheterization. Two independent observers rated their behavior at 15-min intervals over the 3-hour catheterization procedure in categories of affect, arousal and degree of interpersonal engagement. These rated data were used together with information obtained from retrospective interviews to assign each patient to one of the behavioral groups designated anxious-engaged, anxious-not engaged, depressed and calm. Plasma levels of growth hormone, cortisol, free fatty acid and glucose were determined every 30 min during the procedure. Free fatty acid levels rose appreciably in all patients. Calm and depressed patients showed no significant increases in plasma levels of either growth hormone or cortisol. Anxious-engaged patients showed elevations of cortisol but no elevation of growth hormone. Anxious-not engaged patients showed elevations of both growth hormone and cortisol. The several patterns of hormonal change may reflect different neural organizations underlying the several types of coping behavior.Plasma growth hormone levels in man are labile and have been shown to increase in response to different stimuli such as insulin-induced hypoglycemia, surgical pro-