Abstract: Objective To investigate the possibility of tumor abnormal protein(TAP),as index of diagnosis and prediction of prognosis in gastrointestinal tumors(GITs).Methods The outpatients and inpatients as well as healthy physical examinees in our hospital were chosen as objects in the present study.The patients were divided into GIT group(120 cases),high-risk GIT group(123 cases)and normal group(117 cases).TAP expression was detected in three groups.These study objects were followed up for one and a half years.Then the relationship between TAP expression and the occurrence or recurrence of tumors was analyzed.Results There were significant differences(P＜0.001)among the three groups on the positive TAP with critical expression rate.TAP detections to GITs diagnosis sensitivity,specificity,positive predictive value,negative predictive value and Youden index were 88.33%,85.83%,75.71%,93.64% and 0.74 respectively.TAP positive non GITs crowd tumorigenesis proportion(23.53%)was significantly higher than that of TAP-negative(0.49%)(P＜0.001).GITs TAP positive patients relapse rate(33.33%)was significantly higher than negative ones(6.90%)(P＜0.001).Conclusion TAP can be an index for diagnosis,early prevention,monitoring of treatment effect and prediction of prognosis of gastrointestinal tumor.