The diagnostic evaluation of an infertile couple should be thorough and completed as rapidly as possible. The primary diagnostic steps in the workup of the infertile couple include (1) documentation of ovulation by measurement of basal body temperature (BBT) or mid-luteal phase serum progesterone; (2) semen analysis; (3) postcoital test; (4) hysterosalpingogram; and (5) endometrial biopsy. Women should record their BBT for evidence of ovulation. In addition, serial serum progesterone levels may be helpful to confirm ovulation. Serum progesterone values should be obtained 7 days after ovulation and may also be helpful in evaluating inadequate luteal phase. An endometrial biopsy may also provide valuable information regarding the status of the luteal phase. The biopsy is obtained 12 days after the thermogenic shift, or 2 to 3 days before the expected onset of menses, on about day 26 of a 28-day cycle. A postcoital test is an in vivo test that evaluates the interaction of sperm and cervical mucus. It is performed during the periovulatory period up to 12 h after coitus. The cervical mucus is obtained, and its quantity and quality as well as its interaction with the sperm are evaluated. The hysterosalpingogram is performed in the mid follicular phase in order to evaluate the fallopian tubes and the contour of the uterine cavity; it should not be done while the patient is menstruating or after ovulation has occurred. Although gonadotropin levels are not routinely evaluated, they should be obtained in the early follicular phase when testing is indicated, e.g., in cases where there is a history of oligoovulation.