Endogenous nitric oxide (NO) in exhaled air from anaesthetized rabbits was monitored by chemiluminescence. Ethanol (3-30 mmol kg-1) infused i.v. dose dependently reduced the levels of exhaled NO, with an IC50 of 23 +/- 3 mmol kg-1. L-Arginine (1 g kg-1) did not reverse the effect of ethanol. These results demonstrate the inhibition of NO formation by ethanol in vivo.