Background/aim: The aim of this study was to determine the antioxidative effect of curcumin on nicotine-induced mice testis. Materials and methods: Sixty Swiss albino male mice were divided into five groups, each containing 12 mice. The first group was used as a control. To induce toxicity in the second and third group, nicotine (0.4 mg/kg/day) was injected intraperitoneally into mice for 14 and 28 days, respectively. The mice in the fourth and fifth group were injected with nicotine (0.4 mg/kg/day) and orally treated with curcumin (200 mg/kg) for 14 and 28 days, respectively. Testosterone levels were measured from blood samples and testis tissues were examined under light and electron microscopes. Results: Light and electron microscopic examinations of the nicotine-induced groups showed evident degenerations in spermatogenic cells, Sertoli cells, and Leydig cells. The groups treated with curcumin had less testicular alterations. The mice that were sacrificed after 28 days in the groups treated with curcumin showed minor degenerations. Furthermore, the median levels of testosterone significantly decreased in the nicotine-induced groups in comparison with those in the control group. Conclusion: The results indicated that curcumin might be a potential therapeutic agent for testicular injury caused by nicotine addiction.