Background: Inguinal hernia repair is the most common operation in general surgery. Prosthetic reinforcement of the inguinal area with polypropylene mesh has increased dramatically in the last decade. The aim of this study was to evaluate how different types of mesh affect the spermatic cord structures. Methods: Thirty rats were divided into three groups. The spermatic cord was dissected free and a conventional suture repair was performed in group I, an operation mimicking the Lichtenstein operation with a heavyweight polypropylene mesh in group II and the same operation using large pore, lightweighted polypropylene/polyglactin composite mesh in group III. A vasography was performed after 90 days. The cross-sectional area of the vas deferens and s-testosterone from the spermatic vein were measured using the contralateral side as control. Light microscopy of the inguinal canal was performed and inflammation and fibrosis were graded. Results: Vasography revealed patent vas deferens in all animals. In group III, there was a lower s-testosterone in the spermatic vein and a reduced cross-sectional area of the vas deferens on the operated compared to the control side. However, there was no difference in the other groups and there was no significant difference in s-testosterone levels between the groups. There was significantly more inflammation and fibrosis after mesh repair compared to suture repair, but there was no difference between the two mesh groups. Unexpectedly, polyglactin fibres were still seen in specimens in group III after 90 days. Conclusion: In conclusion, the only effect on the spermatic cord structures in a rat model is seen as an impaired s-testosterone production and a reduced cross-sectional area of the vas deferens after use of a low-weight composite mesh compared to the control side. No difference in inflammation or fibrosis was found between heavyweight polypropylene mesh and low-weight composite mesh.