Infertility is a global problem affecting 15% of couples in the world. Male factor is responsible to half of all infertility cases. In 25% of male infertility cases men have normal sperm parameters but unable to fertilize their partners, these cases are classified as idiopathic infertility. The aim of this study was to investigate the oxidative stress status in semen and serum of idiopathic infertile men. Semen and blood samples were collected from infertile and fertile subjects, semen was analyzed according to WHO 2010 guideline, and oxidative stress marker were estimated.