Infertility is defined as the inability to achieve pregnancy after one year of regular, unprotected intercourse. Evaluation may be initiated sooner in patients who have risk factors for infertility or if the female partner is older than 35 years. Causes of infertility include male factors, ovulatory dysfunction, uterine abnormalities, tubal obstruction, peritoneal factors, or cervical factors. A history and physical examination can help direct the evaluation. Men should undergo evaluation with a semen analysis. Abnormalities of sperm may be treated with gonadotropin therapy, intrauterine insemination, or in vitro fertilization. Ovulation should be documented by serum progesterone level measurement at cycle day 21.