We have previously shown a relationship between plasma endotoxin levels and severity of alcoholic liver injury in the intragastric feeding rat model. We attempted to reduce both circulating endotoxin and liver injury in this model by administering a lactobacillus strain (species GG) which survives for prolonged periods in the gastrointestinal tract. Male Wistar rats were fed ethanol and liquid diet containing corn oil (CO+E). Another group of animals (CO+E+L) received the diet containing ethanol plus a daily bolus of lactobacilli GG concentrate (10(10) CFU). All animals were sacrificed after one month. All animals had plasma endotoxin measurements and evaluation of severity of pathologic changes in the liver. The weight gain and blood alcohol levels were similar in both groups. The mean +/- SE of the pathology score was significantly higher (3.4 +/- 0.85) in the CO+E group compared to the CO+E+L group (0.5 +/- 0.3, P < 0.01). The virtual absence of pathologic changes in the latter group was accompanied by significantly lower endotoxin levels (8.4 +/- 2.9 pg/ml in CO+E+L group vs 48.3 +/- 7.8 pg/ml in CO+E group, P < 0.01). Feeding of strains of lactobacilli that survive in the gastrointestinal tract reduces endotoxemia and alcohol-induced liver injury in the rat. Lactobacillus species GG provides a potential nontoxic form of therapy for both endotoxemia and alcoholic liver disease.