The purpose of this paper is to evaluate the significance of two CT findings: evidence of an exophytic component of part of a hydatid cyst and dilated ducts in the vicinity of a cyst. The CT scans and clinical records of 63 patients were reviewed. There was evidence that cysts with an exophytic component are probably unstable and unsuitable for treatment by percutaneous drainage or prolonged medical treatment. Dilated pericystic ducts are a relative contraindication to nonsurgical treatment because of the danger of complicating biliary obstruction. Surgery should not be delayed unduly when either sign is encountered.