Intestinal ischemia is a common condition in critically ill patients and has been postulated to play a role in the development of organ failure and death. This has resulted in the recent interest in monitoring gastric intramucosal pH (pHi) in critically ill patients to provide earlier evidence of inadequate resuscitation, cardiogenic dysfunction, or sepsis. Several reports have indicated that low pHi values obtained during the initial 24 to 48 hours of intensive care unit (ICU) admission were associated with the development of organ failure and death. The purpose of this study was to assess the predictive value of serial pHi measurements obtained throughout the entire ICU admission. A retrospective analysis of critically ill trauma, burn, and surgical patients who had frequent pHi determinations during ICU treatment was performed. When stratified by pHi values, there were no significant differences in length of stay, organ dysfunction, or mortality. Our findings suggest that serial pHi determinations obtained beyond the early critical care period are less reliable predictors of poor outcome.