Abstract: AIM: To study the effect of chlorotoluron system on the tesis of mice.Methods: Male mice were contaminated with chlorotoluron by oral for 25 days.Results: It indicated that all doses of herbicide had different changes.It was detected that under the light microscope seminaferous epithelium arrayed loosely and disorderedly, spermatogenic cell shed, layers lessened, while under the electron microscope mitochondria in the seminaferous epithelium appeared vacuolated, karyotheca swelled and bent, the amount of sustentacular cell declined, and part of tight junction destroyed.Conclusion: The trend of degeneration and more seriously pathological changes appeared with increasing doses.

Key words: chlorotoluron, mice, testicle