Khat (Catha edulis Forsk) is a dicotyledonous evergreen shrub of the family Celastraceae that grows in parts of East Africa and Yemen. Fresh leaves and stem tips or twigs of the plant are chewed for their euphoric properties. The habit of khat chewing is increasing remarkably and its health effects are not much known to the users. The study is aimed at investigating the toxic effects of khat extract on male gonad, the testes by assessing the histological changes of the testes as well as changes in serum testosterone level and amount of glycogen in testicular tissue. The organic extract of khat leaves at different doses were chronically administered to different age groups of mice. By means of qualitative histopathological examinations and quantitative histomorphometric investigations, as well as through testosterone and glycogen assays, the toxic manifestations of the extract was assessed at various doses. The results were compared with the control groups and statistically analyzed.