Infertility is the inability to achieve a pregnancy after 12 months of regular, unprotected sexual intercourse. Evaluation and treatment are recommended earlier than 12 months when risk factors for infertility exist, if the female partner is 35 years or older, and in the setting of nonheterosexual partnerships. A comprehensive medical history and physical examination emphasizing the thyroid, breast, and pelvic areas should be performed to help direct diagnosis and treatment. Causes of infertility in females include uterine and tubal factors, ovarian reserve, ovulatory dysfunction, obesity, and hormone-related disorders. Common male factor infertility issues include abnormal semen, hormonal disorders, and genetic abnormalities. Semen analysis is recommended for the initial assessment of the male partner. Evaluation of the female should include assessment of the uterus and fallopian tubes with ultrasonography or hysterosalpingography when indicated. Laparoscopy, hysteroscopy, or magnetic resonance imaging may be needed to evaluate for endometriosis, leiomyomas, or evidence of a previous pelvic infection. Treatment with ovulation induction agents, intrauterine insemination, in vitro fertilization, donor sperm or eggs, or surgery may be necessary. Unexplained male and female infertility can be treated with intrauterine insemination or in vitro fertilization. Limiting alcohol intake, avoiding tobacco and illicit drug use, consuming a profertility diet, and losing weight (if obese) may improve pregnancy success rates.