Pulmonary edema following i.v. contrast medium injection is a rare adverse reaction. We report on a 71-year-old woman who developed pulmonary edema following i.v. injection of iohexol during spiral CT of the thorax. She developed shortness of breath during the injection, and the first radiographic signs of pulmonary edema were visible on CT images 25 s after the onset of injection. On HRCT images 15 min later, marked edema was demonstrated in both lungs in a mosaic pattern of distribution. After appropriate therapy, the patient recovered without sequelae. A repeat CT 6 days later showed complete normalization.