Sheep that were habituated to drinking 10% (vol/vol) ethanol solution instead of water were subjected to proven thirst stimuli to study the effect of chronic ethanol intake on brain mechanisms subserving thirst. Sheep that had not previously drunk 10% ethanol were also tested. All sheep were trained to press a pedal that delivered 50 ml/press of fluid (either 10% ethanol or water) into a drinking cup. In some experiments, fluids were presented in bins. All animals had access to only one fluid at a time. Five ethanol-drinking sheep appeared healthy and maintained body weight over 18 mo. They always preferred water to 10% ethanol. The intracerebroventricular (icv) infusion of angiotensin II (ANG II) at 3.8 micrograms/h for 2 h increased ethanol intake from 15 +/- 10 to 200 +/- 55 ml in the 1st h, but 2,850 +/- 320 ml of water was drunk in the 2nd h. The icv infusion of 500 mM NaCl had a similar effect. After fluid deprivation for 22 or 46 h, ethanol intake in 1 h of access was only 280 +/- 40 and 400 +/- 90 ml, respectively, and 24-h intake was not increased. Water-drinking sheep drank 1,300 +/- 195 ml of water in 1 h after 22-h water deprivation, and 24-h intake was 1.5 times normal. The icv infusion of ANG II in these sheep increased water intake in 1 h from 10 +/- 10 to 1,630 +/- 250 ml and intake of 10% ethanol to only 310 +/- 60 ml. In conclusion, sheep accept 10% ethanol as a substitute for water for daily drinking.(ABSTRACT TRUNCATED AT 250 WORDS)