After the initial infertility evaluation, if nothing specific cause is found; “unexplained infertility” is diagnosed. Approximately 20% of fertility patients are diagnosed with unexplained infertility. Treatments for unexplained infertility include intrauterine insemination (IUI) with either oral or injectable medications like clomiphene citrate (oral medication) or with (injectable) FSH stimulation, or in vitro fertilization (IVF). With unexplained infertility, the monthly conception rate without clinical treatment is low (under 5%). Thus, treatments that improve upon that are utilized. The chance of becoming pregnant after 3 or 4 treatment cycles of IUI with clomiphene is about 20 to 25%; with IUI with injectable FSH is about or 30 to 35%, and with IVF is as high as 75 to 85% in young women. Age is important with regard to success rates. Usually, treatment begins with IUI with clomiphene for 3 to 4 cycles. If that is unsuccessful, either IUI with FSH or IVF is considered. This choice is made after weighing the costs, success rates, and especially multiple pregnancy rates, given the high risk involved. IVF may be chosen because of its higher success and lower risk for triplets. In addition, there is more control over multiple pregnancy risk since one may choose to transfer fewer embryos. With more liberal use of elective single embryo transfer, the multiple pregnancy rate with IVF will continue to diminish. The goal should be to arrive at a singleton pregnancy in the safest way possible and as quickly as is appropriate for that couple.