While both ethanol and gut ischemia/reperfusion (I/R) are known to alter hepatic microvascular function, little is known about the influence of ethanol consumption on the hepatic microvascular responses to I/R. The objective of this study was to determine whether acute ethanol administration exacerbates the hepatic microvascular dysfunction induced by gut I/R. Rats were exposed to gut ischemia for 30 min followed by reperfusion. Intravital videomicroscopy was used to monitor leukocyte recruitment and the number of nonperfused sinusoids (NPS). Plasma ALT, tumor necrosis factor (TNF)- and endotoxin concentrations were monitored. In separate experiments, ethanol was administered 15 min or 24 hr before gut ischemia. In control rats, gut I/R increased the number of stationary leukocytes and NPS. It also elevated the plasma ALT, TNF- and endotoxin, with a corresponding increase in IMP. Low-dose ethanol consumption 15 min before gut ischemia blunted the gut I/R-induced leukostasis and elevations in plasma TNF- and ALT. However, high-dose ethanol consumption aggravated the gut I/R-induced increases in leukostasis and increases in plasma endotoxin and ALT. When ethanol was administered 24 hr before, high-dose ethanol aggravated the gut I/R-induced hepatocellular injury, but low-dose ethanol did not have any effects on it. These results suggest that low-dose ethanol consumption shortly before gut ischemia attenuates the hepatic inflammatory responses, microvascular dysfunction and hepatocellular injury elicited by gut I/R, while high-dose ethanol consumption appears to significantly aggravate these gut I/R-induced responses.