Some couples are infertile even when we are unable to define the cause of their infertility. When all available tests show that the reproductive system of both the partners is normal, that is semen analysis is adequate, ovulatory functions are normal, no problem is detected inhysterosalpingogram or laparoscopy, we call it unexplained infertility. Just a few years ago unexplained infertility was reported in upto 60% of patients. Recently its prevalence is reported between 10 to 15%. The diagnosis of unexplained infertility can be highly frustrating for the couple because they may consider that as no cause of their infertility could be found, thereby meaning that doctor does not have any effective treatment for their problem. It is very important to know that the unexplained infertility is a diagnosis of exclusion. This does not mean that the couple does not have any cause for their infertility but merely that we, presently, are unable to tell the cause of their not conceiving.