For a long period, ethno medicinal plants have been a valuable source of natural products for maintaining human health, especially in the last decade, with more intensive studies for natural therapies. The use of ethno medicinal plant for pharmaceutical purposes has gradually increased in Iran. Gundelia tournefortii has been used as an antibacterial, anti-fungal, antipyretic, anti-inflammatory, and antioxidant agent in Iran. In the recent examination, the testicular protective effect of G. tournefortii aerial parts aqueous extract on diabetic mice has been evaluated. Seventy mice were used and diabetes was induced by administration of 150 mg/kg of alloxan monohydrate intraperitoneally in 60 mature male mice and they were randomly divided into six groups. The treatment groups received glibenclamide 10 mg/kg and 5, 10, 20 and 40 mg/kg of G. tournefortii through gavage for 20 days. Also, one group was considered as the non-diabetic control. At 20th day, the mice were killed, dissected, then blood and testis samples were collected for biochemical and stereological parameters analysis. The data were analyzed by SPSS-21 software. G. tournefortii at all doses (especially GT40) and glibenclamide significantly (p≤0.05) ameliorated the concentrations of fasting blood glucose, testosterone, superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase. Also, multiple doses of G. tournefortii (especially GT40) and glibenclamide increased the weight and volume of the testis, the volumes of the tubule and interstitial tissue, the length and diameter of the tubule, the height of the germinal epithelium, and the number of the Leydig cell compared to the diabetic untreated group. According to the obtained results, G. tournefortii aerial parts aqueous extract can regulate the concentrations of biochemical parameters and inhibit testicular damages in alloxan monohydrate induced diabetic mice. It seems that G. tournefortii can be offered as a testicular protective supplement or drug for prevention, control, and treatment of testicular toxicity in diabetic patients.