Intrauterine insemination is a commonly performed procedure in cases of infertility. It is especially done in couples with unexplained infertility, since unexplained infertility has no agreed upon treatment plan.Reactive oxygen species (ROS) has been proved to cause damage to sperm, including its motility, fertilizing capacity and sperm DNA. The use of antioxidants in treatment of male infertility has been an extremely controversial issue. The studies that were done on the use of oral antioxidant supplementation in cases of male subfertility yielded contradictory results. The use of in vitro antioxidant addition also showed different outcomes on ROS caused damage. In this study, antioxidant addition during semen preparation was done. After this, the processed semen plus antioxidant was used for intrauterine insemination. These steps were performed in couples with unexplained infertility and the pregnancy rate was monitored. Antioxidant addition was done to counteract the effect of ROS present in the semen and its effect on sperm. Also, to neutralize the effect of the oxygen species generated during semen preparation.