The effects of epinephrine administration on cardiovascular function were examined in 26 men who were given a bolus injection of either 1:10,000 epinephrine hydrochloride or physiological saline. Impedance cardiographic and continuous blood pressure measures were recorded during a 2-min pre-injection baseline and in the post-injection period. Compared to a saline control, epinephrine elicited greater shortening of heart period, pre-ejection period, and the R-B interval; greater increases in cardiac output, stroke volume, dZ/dt amplitude, Heather Index, and systolic and diastolic pressures; and greater decreases in total peripheral resistance (all P < 0.05). Left ventricular ejection time and the Q-R interval were not affected. The results indicate that inotropic indices that are readily measured by impedance cardiography should be considered as important non-invasive indices of adrenergically mediated responses to stress.