Large-bowel obstruction (LBO) is a relatively common abdominal emergency. The CT exam has become the most important imaging modality for the diagnosis of LBO, following abdominal ultrasound and plain radiography. The recent multi-detector CT (MD-CT) is able to clarify the etiology of LBO and to help in deciding how to treat LBO. Therefore, it is important for the radiologists to become familiar with the imaging findings of LBO, including plain radiograph and CT, due to various causes. In this article, we have shown the characteristics of the radiological findings including plain radiograph, barium study, and CT as well as their correlations with pathologic findings of LBO. The etiology of LBO is usually divided into neoplastic diseases and nonneoplastic diseases. However, the most common cause is the neoplastic etiology. Now, we can afford the critical information concerning the level of obstruction, its cause, the viability of the involved bowel loops, and a decision-making regarding the therapy for patients with LBO, using MD-CT high technology.