Oxidative stress (OS) has been considered a major contributory factor to the infertility. to provide a cryoprotective effect on mammalian sperm quality. This paper reviews the impacts of oxidative stress and reactive oxygen species on spermatozoa functions causes of ROS generation and antioxidative strategies to reduce OS. In addition we also spotlight the emerging concept of utilizing OS as a tool of contraception. 1 Introduction Gametes are susceptible to reactive oxygen species (ROS) attack. When manipulated during assisted reproductive techniques these cells run the risk of generating and being exposed to supra-physiological level of ROS . Defective sperm functions are the most prevalent causes of male infertility and a difficult condition to treat . Many environmental physiological and genetic factors have been implicated in the poor sperm functions and infertility [3-6]. Thus it is very important to identify the factors/conditions which impact normal sperm functions. Among numerous causes oxidative stress (OS) has been attributed to impact the fertility status and physiology of spermatozoa . The term LY310762 oxidative stress is generally applied when oxidants outnumber antioxidants . The imbalance between the production of reactive oxygen species (ROS) and a biological systems ability to readily detoxify the reactive intermediates or very easily repair the producing damage is known as oxidative stress . The main destructive aspects of oxidative stress are the production of LY310762 ROS which include free radicals and peroxides . The production of ROS by sperm is usually a normal physiological process but an imbalance between ROS generation and scavenging activity is usually detrimental to the sperm and associated with male infertility . Physiological levels of ROS influence and mediate the gametes [11-13] and crucial reproductive processes such as sperm-oocyte interactions  implantation and early embryo development . Against ROS attack sperm cells are well equipped with a strong defense system of antioxidants . Antioxidants are the main defense factors against oxidative stress induced by free radicals .This short article reviews the impact of oxidative stress and reactive oxygen species (ROS) on spermatozoal functions causes of ROS generation and antioxidative strategies to reduce the oxidative stress. In addition the significance of antioxidants in reproduction and oxidative stress as a contraceptive measure will be examined. 2 Oxidative Stress One of the most important factors contributing to poor quality semen LY310762 has been reported to be oxidative stress . Oxidative stress is a condition associated with an increased rate of cellular damage induced by oxygen and ARHGAP1 oxygen derived oxidants commonly known as ROS . Uncontrolled production of ROS that exceeds the antioxidant capacity of the seminal plasma prospects to oxidative stress (OS) which is usually harmful to spermatozoa . All cellular components LY310762 including lipids proteins nucleic acids and sugars are potential targets of oxidative stress . 3 Free Radicals Free radicals are short lived reactive chemical intermediates which contain one or more unpaired electrons [19 20 They induce cellular damages when they pass this unpaired electron onto nearby cellular structures resulting in oxidation of cell membrane lipids amino acids in proteins or within nucleic acids . Free radicals are also known as a necessary evil for intracellular signaling involved in the normal process of cell proliferation differentiation and migration [22-24]. In the reproductive tract LY310762 free radicals also play a dual role and can modulate numerous reproductive functions . Excess of free radicals generation frequently involves an error in spermiogenesis resulting in the release of spermatozoa from your germinal epithelium exhibiting abnormally high levels of cytoplasmic retention . 4 Reactive Oxygen Species (ROS) ROS are created as necessary by-products during the normal enzymatic reactions of inter- and intracellular signaling. Mammalian spermatozoa symbolize a growing list of cell types that exhibit a capacity to generate ROS when incubated under aerobic conditions such as.