Common causes of subfertility include ovulatory disorders, tubal disease, peritoneal adhesions, endometriosis, uterine abnormalities, abnormalities of sperm and advancing female age. Infertility is unexplained after thorough evaluation in about 5-10% of cases. Significant caveats must be attached to the interpretation of available data regarding infertility treatments. Successful ovulation induction in anovulatory women is possible for nearly all women except in cases of ovarian failure. Surgery is an option for some patients with tubal damage, adhesions, endometriosis and uterine abnormalities. Male factor infertility may be amenable to treatment of a specific cause, but is often empirical with the use of intra-uterine insemination (IUI) or in vitro fertilization (IVF). Egg donation is currently the most effective treatment available for age-related infertility when other treatments have not been successful. Couples with unexplained infertility may be effectively treated with ovulation induction plus IUI or IVF.