Introduction: Reactive oxygen species (ROS) in the seminal fluid are derived from abnormal sperm, white blood cells or both. Oxidative stress will cause lipid peroxidation, decreased sperm motility and abnormalities in sperm fertilizing capacity. The aims of this study were to compare sperm parameters (Sperm count, motility and morphology) in infertile men with or without leukocytospermia and to measure both seminal total antioxidant capacity (TAC) and malon-dialdehyde (MDA) concentration.Materials and Methods: This case-control study included 110 male subjects referring to Kashan Infertility Center during 2007-2008. Regarding the World Health Organization criteria and following sperm analysis and seminal leukocyte counts, the cases were divided into two leukocytospermic and non-leukocytospermic groups and a third group composed of 45 men with normal test results were selected as the controls. Seminal plasma MDA and TAC levels were spectrophotometrically measured.Results: Upon semen analyses of 110 subjects, 45 individuals were classified as healthy, 30 as leukocytospermic and 35 as non-leukocytospermic; although there were