The features of computed tomography (CT) in 5 patients with hydatid disease of the urinary tract are described. The diagnosis of hydatid disease was based on the demonstration of unilocular or multilocular cysts with well defined walls which enhanced with contrast, which were often calcified and which contained daughter cysts within the large parent cyst. It is difficult to differentiate between a unilocular hydatid cyst without mural calcification and an infected simple renal cyst.