The effect of chronic enteral ethanol on pancreatic hypoxia was investigated using the hypoxia marker, pimonidazole. Male Wistar rats were fed an ethanol-containing diet for 3 weeks using an enteral model shown to cause pancreatic damage; pimonidazole (120mg/kg i.v.) was injected 1h before sacrifice. Pimonidazole and 4-hydroxynonenal (an index of lipid peroxidation) adducts were detected immunochemically. Breathing air with low oxygen content (8% O₂) for 1h increased pimonidazole adduct accumulation ∼2-fold in pancreata of naı̈ve rats, confirming that this technique will detect increases in hypoxia in pancreata. Pancreata of rats fed ethanol began to show signs of damage after 3 weeks. Ethanol feeding also significantly increased pimonidazole adducts in pancreas ∼2-fold (1 or 3 weeks of ethanol produced similar values). Concomitant with increasing hypoxia in the pancreas, alcohol also caused a significant increase in 4-hydroxynonenal adducts, indicative of increased oxidative stress. These results indicate that chronic ethanol causes hypoxia at the cellular level in the pancreas in vivo; further, the data support the hypothesis that hypoxia is involved in mechanisms of chronic alcoholic pancreatitis.