Intrauterine insemination (IUI) is a simple first line treatment for infertile couples (1). This inexpensive treatment, in comparison with other assisted reproductive techniques (ART), has been widely used to treat infertile couples with a variety of indications such as male subfertility, unexplained fertility, cervical mucus hostility and endometriosisrelated infertility. (2-7) Pregnancy rates after IUI differ between studies according to patient selection criteria, the presence of various infertility factors, ovarian stimulation methods, number of cycles performed, different sperm parameters, and preparation %). There was no triple or higher order multiple pregnancies. At the end of the sixth cycle, 73 clinical pregnancies had been achieved (89.0% %). After diagnostic laparoscopy, the pregnancy rate per cycle for patients 35 years age was 18% %, which is significantly higher than that of patients 35 years of age. Pregnancies occurred up to the fifth cycle after laparoscopy. The pregnancy rate (PR) per cycle was significantly higher in cases of sperm movement rates more than 30% % (PR 9.3% %) and total motile sperm counts more than 10 10 6 /ml (PR 8.2% %). A study comparing the washed and unwashed cases did not reveal any differences. Conclusion : In male sub-fertility cases of sperm parameters as motility rates 30% % and motile sperm concentration 10 10 6 /ml, IUI could be a useful option for infertility treatment J. Med. Invest. 58 : 127-133, February, 2011 ORIGINAL Effect of semen characteristics on pregnancy rate following intrauterine insemination