Unexplained infertility is a diagnosis made by exclusion after a complete infertility evaluation. Standard testing for infertility should include semen analysis (evaluated according to the WHO criteria), assessment of ovulation (serum progesterone determination in the midluteal phase), and an evaluation of tubal patency. At present, other additional investigations contribute relatively little to effective diagnosis of unexplained infertility. Laparoscopy is required to make a diagnosis of endometriosis or adnexal adhesions, but in the presence of tubal patency, these lesions seem to be of lesser significance. The use of intrauterine insemination (IUI) together with ovulation induction in normally ovulating women carries a risk of ovarian hyperstimulation syndrome and multiple pregnancy. Based on the available information, it is reasonable to recommend an escalating course of gonadotropin ovarian stimulation with IUI and then in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI).