Physicians can play an important role in the prevention of infertility through aggressive treatment of pelvic infections and improved surgical techniques. The cause of infertility can be diagnosed 90 percent of the time. Ovulation, tubal, peritoneal, uterine, and cervical factors should be evaluated. Sperm-cervical mucus interaction should be assessed. Basal body temperature charts are simple and reliable. An endometrical biopsy should be timed for 8 to 10 days after ovulation, histologically dated, and compared with basal body temperatures. Tubal factors are best assessed by hysterosalpingogram and treated by microsurgery. The incidence of pelvic factors increases with age, prior infection, previous surgery, and pelvic pain. Cervical mucus can be studied and changes quantitated by using a simple scoring system. Uterine anomalies increase pregnancy risk but do not usually cause infertility. Clomiphene therapy should be limited to women who ovulate infrequently or not at all. Estrogen improves cervical mucus production; progesterone treats luteal phase defects. Infertile patients are often angry, anxious, and depressed, and additional time should be set aside during an office visit for optimum communication.