The hydrophobic surface layer of the gastrointestinal (GI) tract, which has been attributed to the presence of phosphatidylcholine (PC) in the mucus gel, protects the mucosa of the GI tract and is disrupted by parenteral LPS treatment. We investigated the potential for repletion of this layer as a means to prevent LPS-induced GI injury. Rats were treated orally with PC 1 h before LPS (i.p.). Gastric and ileal tissues were assessed for changes in permeability 5 h later, and gastric fluid was analyzed for signs of GI-related LPS effects (bile acid reflux, increased volume, and pH) and gastric injury (bleeding). Serum TNF-α was assessed as a measure of a non-GI, LPS response. Radiolabeled PC was tracked through the GI tract to verify the extent of luminal exposure during the time of the study. Pretreatment with oral PC significantly blocked permeability increases in gastric and ileal tissue due to LPS. A portion of orally administered PC gained access to the entire GI tract in 1 h. Exogenous PC did not prevent the increase in serum TNF-α or gastric fluid volume or pH induced by LPS, nor did it prevent the duodenogastric reflux of bile acid. There was a tendency for PC to reduce gastric bleeding after LPS. Orally administered PC seems to act directly on the mucosa to prevent GI permeability disturbances due to LPS. Under the conditions studied, oral PC does not block systemic effects of LPS. However, enteral formulations containing PC may be useful adjuncts in the prevention of GI injury from endotoxemia.