Cymbopogon citratus (C. citratus) has antioxidant, anti-inflammatory, and chemoprotective properties. This study was conducted to evaluate the protective effect of C. citratus aqueous extract against hydrogen peroxide (H2O2)-induced oxidative stress and injury in the reproductive system of male rats. The twenty-five rats used in this study were divided into five groups, comprised of five rats each. The control group received standard food and drink. The H2O2 group received standard food and water with 0.5% H2O2. The rats in the H2O2 + C. citratus group and H2O2 + vitamin E group received standard food, H2O2, and C. citratus [100 mg·kg(-1) body weight (bw)], or vitamin E as an antioxidant reference (500 mg·kg(-1) bw), respectively. The C. citratus group was given C. citratus (100 mg·kg(-1) bw) in addition to the standard food and drink. The treatments were administered for 30 days. The H2O2 treatment significantly (P < 0.05) decreased body, testicular, and epididymal weight, as well as glutathione (GSH) level, but markedly increased malonaldehyde (MDA) in serum and testes homogenates. The rats treated with H2O2 exhibited testicular degeneration and significant reduction in sperm viability, motility, count, and rate of normal sperm. The C. citratus, vitamin E, and H2O2 treatment significantly (P < 0.05) increased the body, testicular, and epididymal weight, testosterone level, the values of the various sperm characteristics, and GSH. However, this treatment markedly reduced MDA in serum and testes homogenates, as well as testicular histopathological alterations in the H2O2-treated rats. The C. citratus aqueous extract reduced oxidative stress and protected male rats against H2O2-induced reproductive system injury.