Gastric mucosal pH reflects splanchnic perfusion. Monitoring gastric mucosal pH might be useful in predicting outcome after liver transplantation. Forty patients were included in the study. Gastric mucosal pH and gastric mucosal pH corrected for systemic pH were compared with regard to initial liver function and morbidity. Eighty percent of the patients had at least one episode with a gastric mucosal pH of <7.32, and 84% of these had a concomitant arterial pH of <7.32. No differences in morbidity were found between patients with a gastric mucosal pH of <7.32 and those with a gastric mucosal pH of >7.32. If gastric mucosal pH was corrected for arterial pH, only 49% of the patients had an episode during transplantation with a corrected gastric mucosal pH of <7.32. Comparing these patients with the group that did not have such an episode, we found that flow in the venovenous bypass system was significantly lower (2.9 v 3.4 L/min; P < .02) in the first group. Also alanine aminotransferase and aspartate aminotransferase levels were higher, antithrombin III levels and lidocaine clearance rates were lower, and prothrombin times were longer in the group with corrected gastric mucosal pH of <7.32. No differences with regard to major morbidity and mortality were noted. Gastric mucosal pH during liver transplantation should be corrected for arterial pH. Patients with a corrected gastric mucosal pH of <7.32 are more likely to develop initial liver function tests disturbances, but morbidity is not different from patients with gastric mucosal pH of >7.32.