Information suggests that there may be gender-based differences in skeletal muscle responses to damaging exercise. Evidence demonstrates that estrogen has strong antioxidant properties and may be an important factor in maintaining postexercise membrane stability and limiting creatine kinase (CK) leakage from damaged muscle in female animals. Research demonstrates effects of estrogen and possible gender differences in other morphological and biochemical indices of postexercise muscle damage and leukocyte invasion. Nevertheless, there are conflicting findings suggesting that in some in vivo exercise models, estrogen administration has limited ability to affect exercise-induced oxidative stress and muscle damage and may cause loss of tissue vitamin C. Gender differences appear to exist in tissue levels of other important antioxidants such as vitamin E and glutathione. More research is needed to fully define the potential for estrogen to influence postexercise muscle damage and the inflammatory response and to determine the mechanisms by which it may operate.