Large-bowel obstruction is an abdominal emergency with high morbidity and mortality rates if left untreated. Although abdominal radiography is usually the initial imaging study performed in patients suspected of having large-bowel obstruction, it may not be sufficient to distinguish obstruction from other causes of colonic dilation. Computed tomography is the imaging method of choice as it can establish the diagnosis and cause of large-bowel obstruction. A contrast agent enema may be used to confirm or exclude large-bowel obstruction. In this review, the imaging findings in multiple causes of large-bowel obstruction are illustrated and compared with acute colonic pseudo-obstruction.