OBJECTIVE Korean red ginseng (KRG) is a potent antioxidant and a free radical scavenger. This study was designed to determine whether KRG could protect against dysfunction and oxidative stress induced by torsion-detorsion injury in rat testis. METHODS Six-week-old male Sprague-Dawley rats were randomly divided into four groups: a sham-operated control group (C), a sham-operated and KRG-treated group (K), a 2 hours torsion and detorsion group (T), and a 2 hours torsion and detorsion and KRG-treated group (T+K). We measured testis weight and hormone levels and reactive oxygen species (ROS) from the left renal vein. Superoxide generation was measured on the basis of lucigenin-enhanced chemiluminescence in testis tissue. RESULTS Testicular weight was significantly higher in the T+K group than in the T group; however, there were no significant differences in hormone levels between the 4 groups. The mean level of ROS and superoxide production was significantly higher in the T group than in the C group, whereas administration of KRG attenuated this increase. Upon histologic evaluation, the T group was found to have cellular disarray, a lack of cellular cohesiveness, degenerative changes in the germinal cells, and less distinct changes in the seminiferous tubules, whereas the T+K group had a germinal epithelial layer that appeared nearly normal. CONCLUSIONS The present study demonstrated that KRG recovered the testis dysfunction in the rat testis by suppressing superoxide production.