The effect of acute (2.0 g/kg, intragastrically) and chronic (8.0-11.0 g/kg/day for 10 days, intragastrically) ethanol exposure on beta-endorphin levels in plasma, hypothalamus and pituitary were examined in rats. Hypothalamic and plasma catecholamines and plasma corticosterone were also measured in these animals. Plasma beta-endorphin, norepinephrine (NE) and corticosterone levels were significantly increased and dopamine (DA) was unchanged in acute and chronic ethanol-treated rats. Compared to controls, plasma epinephrine (E) levels were increased in acute ethanol-treated rats but no significant change was observed in chronic ethanol-treated rats. Plasma dopamine were significantly decreased following chronic ethanol treatment while no significant change was observed after acute treatment. In the hypothalamus, beta-endorphin and dopamine contents were increased and norepinephrine levels were reduced in response to ethanol exposure. Beta-endorphin levels were decreased significantly in the anterior pituitary and the neurointermediate lobe of the pituitary in ethanol-treated animals except in the neurointermediate lobe of the chronic ethanol-treated animals. These findings together suggest that there is an interaction between beta-endorphin, catecholamines, corticosterone and ethanol in response to acute and chronic ethanol exposure in rats.