Intra- or extrapancreatic pseudocyst is a common local complication in pancreatitis. Pathological involvement of the colon secondary to acute and chronic pancreatitis is a rare complication of major clinical interest. Contiguity with the tail of the pancreas and certain anatomical relationships, particularly at the level of the peritoneal reflections, explain the involvement of, particularly, the left flexure of the colon and the adjacent part of the transverse colon. We report a patient, presenting with ileus resulting from pressure of a giant pseudocyst secondary to acute pancreatitis, to share the diagnostic and chronologic follow-up computed tomography (CT) scanning findings of this rare complication. (C) Elsevier Science Inc., 1998.