Vasography may cause stricture of the vas deferens. The probable causes of this obstruction are traumatic lesion at the puncture site and the radiological contrast material used. Because of this problem we performed an experimental study using Wistar rats, which were divided into four groups: Group A - Control, Group B - injection of a saline solution, Group C - hypaque injection, Group D - hypaque plus saline solution. According to the results obtained it was concluded that the needle puncture is not responsible for stricture of the vas deferens. Hypaque is responsible for 5% of strictures and the use of a saline solution to wash the vas did not show any benefit.