The increasing knowledge of the reproductive toxicity of environmental chemicals has raised public concern as to whether the current use of pesticides could adversely affect human reproduction. Among pesticides and their related chemicals, organochlorine insecticides have so far drawn the primary attention. Endosulfan is widely used pesticide due to its quick effect on insects. Endosulfan formulations are used in commercial agriculture and home gardening. They are also used for wood preservation. The present study aimed to illustrate the effect of endosulfan on testosterone level and seminiferous tubule and spermatid in testis of mice. Endosulfan was administrated 2 mg/kg b.w daily by gavage method for five weeks. Mice were sacrificed after completion of schedule, blood were collected for testosterone estimation and tissues for histology. Testosterone level was declined with degenerated seminiferous tubule and spermatid. Primary and secondry spermatocyte were also degenerated after endosulfan exposure. Thus it was concluded that endosulfan exposure causes decline level of testosterone in mice which causes improper spermatogenesis due to degeneration of seminiferous tubule. Spermatid and secondary spermatocyte were also degenerated which causes azoospermic condition leading infertility in mice.