The long-term result of accidental crushing of the vas deferens during inguinal surgery is unpredictable. It is stated that even a slight disturbance in the muscular layer or mucosa may endanger fertility. This study was designed to investigate the early and late histopathologic changes of iatrogenic injury on the vas and its effect on fertility in a rat model. Both vasa deferentia of 54 male rats, divided into three groups (n = 18 each), were subjected to an operative manipulation. These manipulations consisted of digital compression for 45 seconds in group A, grasping with a mosquito clamp for 2 seconds in group B, and grasping with a mosquito clamp for 2 minutes in group C. In five rats from each group, the vasa were removed on the third and 21st postoperative day for histological evaluation. The remaining 13 rats in each group were allowed to mate for a period of 4 months. Bilateral vasa were analyzed for patency and histology. A spermatic granuloma was observed in 79% of the fertile and 80% of the infertile rats. Statistical analysis showed no significant fertility difference among the three groups. There was no statistical difference between groups B and C (P > .05) in terms of high and low flow patency rates in vitro, whereas a statistical significance was present between these two groups and group A (P < .001). It can be said that type rather than time of injury is important in this experimental model, because the results of the patency test alone are sufficient to prove the possibility of functional damage in vas deferens. The authors conclude that inguinal contents should be handled carefully and contralateral exploration in asymptomatic cases older than 1 year with inguinal pathology should be avoided. Copyright (C) 1997 by W.B. Saunders Company.