Objective To investigate the CT manifestation and clinical significance of the gastrointestinal tract involvement in acute pancreatitis (AP). Methods Two hundreds CT scans in 131 patients with acute pancreatitis between Jan. 1, 2009 and Jun. 30, 2009 were included into the study. Two radiologists analyzed the images retrospectively, paying attention to the CT features of the gastrointestinal tract involvement, such as the style, distribution, and so on. The correlation between gastrointestinal tract involvement and CT severity index, clinical severity grading, and turnover of acute pancreatitis were studied using a SPSS 14.0 for windows statistics software. Results The CT images in 109 (83.2%) patients showed gastrointestinal tract involvement, which distributing mainly stomach, duodenum, jejunum, and transverse colon, and showing mainly the gastrointestinal tract wall thickening and distension. The gastrointestinal tract involvement had positive correlation with CT severity index, clinical severity grading, and turnover of acute pancreatitis (r=0.689， P=0.000; r=0.584， P=0.000; r=0.346， P=0.000). Conclusions The gastrointestinal tract involvement is common complication in acute pancreatitis and concerns with severity and prognosis of the disease. As other extrapancreatic organs involvement, the gastrointestinal tract involvement has important value for severity assessment, prognosis evaluation, and therapeutic effect monitoring of acute pancreatitis.