Problem statement: Oxidative Stress (OS) has been recognized as one of the most important cause of male infertility. We studied the relation of serum and Semen Malondialdehyde (MDA) and Total Antioxidant Capacity (TAC) with sperm parameters in infertile men with sperm count within the normal range. Approach: The prospective case- control study performed on infertile men presenting to the infertility clinics of Mirzakochak khan hospital, Tehran university of Medical Sciences from June 2007 to June 2009. The samples were collected consecutively and the total of 40 infertile men was enrolled in the study. Also, 40 healthy men were matched as control group. MDA and TAC in serum and seminal plasma were measured and relation between them and semen analysis parameters were evaluated. The MDA was measured as nmol mL⁻¹ and the TAC was expressed as g dL⁻¹. Results: Analysis showed that the amount of semen MDA was statistically different in infertile and healthy control groups. We did not find any significant relation between smoking and sperm parameters in infertile men. The relation between semen MDA and abnormal sperm abnormal morphology (p = 0.003, r = -0.468) and semen TAC and weak sperm motility (p = 0.037, r = -0.359) was significant. Conclusion: Immediate attention should be directed at simplifying and validating the evaluation of reactive oxygen species and OS status so that it can be performed routinely