CT plays an important role in the evaluation of patients with suspected colonic inflammation. High-resolution, thin-section imaging of the gastrointestinal tract allows assessment of both the intraluminal and extraluminal components of colonic disease, thereby enabling radiologists to detect and stage colonic pathology accurately. In addition, CT can be used to guide percutaneous drainage of abscess collections, often obviating the need for surgical intervention. This article describes CT techniques for diagnosing inflammatory diseases of the colon as well as the typical CT appearances.