Abstract: The purpose of this study was to assess the level of oxidative stress, monitored both by lipid peroxidation, nitric oxide, protein carbonyl oxidation and total antioxidant capacity in seminal plasma from semen collected from fertile rams during the breeding and non-breeding seasons. Oxidative stress in the reproductive system is thought to affect the fertilizing ability of sperm. Seminal oxidative stress status emerges as a significant prognostic tool in assisted reproductive technology. Lipid peroxidation generates physical and chemical stress on the cell membranes of spermatozoa. Normally, there is a balance generation of free radicals between detoxification of them. However, the breakdown of balance causes poor motility viability and fertility of semen. Seminal plasma of rams show differences in before, during and after the breeding season for some oxidative stress parameters.