The effect of Paecilomyces tenuipes water extract (PTWE) on the alcohol metabolism was examined on rats. PTWE of 0, 30, 100 mg/kg body weight was administrated orally to the rats 30 min before oral treatment of 3 g/kg body weight of alcohol. Blood alcohol and acetaldehyde concentrations were measured 0.5, 1, 3, 6, 9 hr after alcohol treatment. Hepatic alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ADH), microsomal ethanol oxidizing system (MEOS) activities were measured 9 hr after alcohol treatment. There were no differences in blood alcohol concentrations and area under the curve (AUC) of alcohol. PTWE decreased acetaldehyde concentration and there were significant differences after 6 hr in 30 mg/kg PTWE and after 3 and 9 hr in 100 mg/kg PTWE, respectively. In particular, 100 mg/kg PTWE decreased AUC of acetaldehyde by 44%. However, there were no changes in the hepatic ADH, ALDH, and MEOS activities.