Testicular toxicity of methotrexate (MTX) is a clinically important adverse effect. Ginseng has been demonstrated to stimulate spermatogenesis, prevent chemotherapy-induced testicular injury and to possess antiapoptotic and antioxidant actions. Owing to its low bioavailability, ginseng was formulated to nanoform in the current study. As there is no available data about the protective effects of ginseng or ginseng nanoparticles against MTX-induced testicular toxicity, this study was initiated. Seventytwo male rats were enrolled. Rats were given either ginseng (5oo mg/kg/day), or ginseng nanoparticles (125 and 250 mg/kg/day) orally for 28 consecutive days. Rats received a single dose of MTX (20 mg/kg) intraperitoneally on day 25. Ginseng and ginseng nanoparticles pre-treatment in rats significantly alleviated the testicular histopathological effects induced by MTX. Also, they significantly restored the impaired spermatogenesis induced by MTX via significantly increasing the Johnsen's tubular biopsy score (JTBS). Ginseng and ginseng nanoparticles treatment prior to MTX administration in rats significantly ameliorated MTXinduced testicular apoptosis by significantly decreasing the percentage of caspase-3-immunostained testicular area. Ginseng and ginseng nanoparticles pretreatment caused nonsignificant increase in serum testosterone levels that were significantly decreased by MTX. The results indicate that ginseng and ginseng nanoparticles protect against MTX-induced testicular toxicity in rats, which is suggested to be through inhibition of MTX-induced testicular apoptosis. The protective effect of ginseng nanoparticles was supposed to be better than ginseng in the given doses.