Methotrexate (MTX) is an inhibitor of folic acid reductase used in managing a variety of malignancies. Testicular injury by MTX is one of its serious adverse effects. The current investigation aims to assess the protective effects of diacerein (DIA) on testicular injury by MTX and clarify the possible underlying mechanisms. Testicular injury in rats was induced by a single injection of 20mg/kg body weight of MTX. DIA was given in 25mg/kg body weight/day and 50mg/kg body weight/day doses for 10days. Compared to the MTX group, DIA attenuated testicular intoxication as evidenced by improvement of testicular histopathological abnormalities and increased serum testosterone and luteinizing hormone. DIA attenuated testicular oxidative stress changes by lowering testicular MDA and boosting GSH content and SOD activity. Moreover, administration of DIA attenuated MTX-induced testicular inflammation, as proved by decreased TNF-α and IL-6. At the molecular level, DIA induced significant upregulation in Nrf2, HO-1, PPAR-γ, and cytoglobin protein expression. The present results proved that DIA, in a dose-dependent manner, exhibited notable amelioration of testicular toxicity induced by MTX through augmentation of anti-inflammatory and antioxidant effects combined by upregulating Nrf2/HO-1, PPAR-γ, and cytoglobin signaling.