Herein we reviewed the computed tomography (CT) findings of a spectrum of pathological entities affecting the duodenum. We discuss the CT findings of some congenital, inflammatory, traumatic, and neoplastic pathologies of the duodenum along with the conventional barium studies of selected conditions. Pathologies of this C-shaped intestinal segment, derived from both foregut and midgut, are often overlooked in clinical practice and radiological literature. While congenital anomalies like duplication cysts and diverticula are usually asymptomatic, annular pancreas and malrotation may manifest in the first decade of life. Primary as well as secondary involvement of the duodenum by various disease processes can be evaluated by careful CT technique and proper attention to the duodenum. Among congenital conditions, annular pancreas, duplication cyst, superior mesenteric artery syndrome, midgut volvulus, and diverticula are presented. Duodenal involvement in adenocarcinoma, lymphoma, gastro­intestinal stromal tumours, Crohn’s disease, and groove pancreatitis are discussed. Duodenal wall haematoma and traumatic duodenal perforation causing pneumoretroperitoneum in two patients after blunt trauma of the abdomen are also illustrated. CT provides superb anatomic detail and offers high diagnostic specificity for the detection of duodenal pathologies because it allows direct imaging of the intestinal wall, secondary signs of bowel disease within the surrounding mesentery, and abnormal findings in adjacent structures. Primary duodenal malignancies and local extension from adjacent malignancies can be diagnosed by CT reliably. CT also plays a vital role in the diagnosis of traumatic duodenal injury by differentiating between mural haematoma and a duodenal perforation because the latter requires immediate surgical intervention.