The purpose of this study was to describe CT findings of colonic involvement in acute non-necrotizing pancreatitis and to analyze the correlation between colonic wall thickening at CT and the clinical course of these patients. The CT examinations of 19 consecutive patients with acute non-necrotizing pancreatitis who were not treated with antibiotics initially were analyzed retrospectively. The severity of acute pancreatitis was categorized according to the CT severity index (CTSI) and the presence of colonic wall thickening at the initial CT was compared with the clinical course of all patients. Seven of 11 patients with a CTSI of 4 showed a colonic wall thickening, whereas the remaining patients with a CTSI of 4 (n=4), CTSI of 3 (n=5), and CTSI of 2 (n=3) showed no colonic abnormalities at CT. Patients with colonic wall thickening presented more often with fever, showed higher levels of infectious parameters, needed more often antibiotic therapy, and had more requests for additional CT examinations and CT-guided fluid aspirations as well as a longer duration of hospital stay as compared with patients without colonic wall involvement, even if the latter presented with the same CTSI initially. It is well known that translocation of the colonic flora may significantly influence the clinical course of patients with acute pancreatitis, and our results indicate that patients with acute pancreatitis who present with colonic wall thickening at CT have an increased risk for a complicated clinical course regarding systemic infection.