In a review of our cases presenting with urethral strictures, we noted a high incidence following open heart surgery. In an attempt to elucidate factors predisposing to the occurrence of urethral stricture, we studied the following data; preoperative laboratory study, aortic clamp time, dosage of heparin and protamine, degree of hypothermia, platelet count, and blood pressure. No significant differences were found between the stricture group and the non-stricture group. Of 33 patients admitted in our hospital with urethral stricture, 8 had suffered after open heart surgery. We believe that the urethral catheter is at least partly responsible for stricture formation. Associated factor, for example urethral ischemia, may be contributory.