We investigated the effects of ethyl pyruvate (EP) on oxidative and endoplasmic reticulum (ER) stress due to experimental testicular ischemia-reperfusion (I-R). Eighteen rats were divided into a control group, a torsion-detorsion (T-D) group and an EP group. For pretreatment of the EP group, 50 mg/kg EP was given intraperitoneally (i.p.) 30 min before detorsion. Tissue 4-hydroxynonenal (4-HNE) and 78-kDa glucose-regulated protein (GRP78) levels were determined using enzyme-linked immunosorbent assay (ELISA) kits. Tissue total oxidant status (TOS) and total antioxidant status were determined using colorimetric methods. Histology of the tissues was evaluated using hematoxylin and eosin staining. In the T-D group, tissue 4-HNE, GRP78, TOS and oxidative stress index levels were significantly higher than for the control group. The increases were reduced significantly by EP pretreatment. Our findings suggest that EP can inhibit I-R induced testicular injury by suppressing oxidative and ER stress. EP may be a useful adjunctive treatment for surgical repair in humans.