Glycowithanolides (Withaferin A), is one of the main withanolides active principle isolated from plant Withania somnifera and is claimed that it possess the aphrodisiac, sedative, rejuvenate and life prolonging properties.In the present investigation, antioxidant activity of active principles of Withania somnifera was tested against D-galactose induced oxidative stress in mouse testes, epididymis and seminal vesicle.For the present investigation Swiss male albino mice Mus musculus (Linn) were used. They were grouped in to control (I), D-galactose treated (II), protective (III) and curative groups (IV). Oxidative stress was induced in six month old mice by injecting a low dose of D-galactose. Antioxidant effect of plant extract was studied in testes, epididymis, and seminal vesicle of oxidative stressed mice on Lipid peroxidation (LPO) and fluorescence product.In the present study, both total as well as mitochondrial lipid peroxidation and fluorescence product in testes, epididymis and seminal vesicle were increased in D-galactose induced mice. After the treatment of glycowithanolides there was significantly decrease in total as well as mitochondrial lipid peroxidation and fluorescence product in protective and curative groups.Our results indicate that Withania somnifera has a capability of preventing oxidative stress and also combating stress induced infertility.