The effect of ethanol on dopamine (DA) metabolism in two selectively bred lines of rats, one alcohol-preferring (sP) and the other--non-preferring (sNP), was studied. Ethanol administration (2 g/kg per os) produced in the two lines of rats a decrease of DA content and an increased concentration of 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the caudate nucleus, olfactory tubercle and medial prefrontal cortex in both lines, but the effect was significantly greater in sP than in sNP rats. Moreover, in sP rats, the voluntary consumption of ethanol increased DOPAC and HVA levels in the above areas. In these animals, DOPAC and HVA accumulation was associated with a small depletion in DA content, suggesting that ethanol releases DA from stores.