The aim of this chapter is to focus on the hyperprolactinemia and infertility. Hyperprolactinemia can be defined as the presence of abnormally high level of prolactin in the blood. This hormone is produced by the pituitary gland which is located at the base of the brain. The main function of prolactin is to stimulate breast milk production after childbirth. High prolactin levels are associated with anovulation and cause directly or indirectly infertility. The prevalence of hyperprolactinemia varies in different patient population, stays below 1% (0.4% in an unselected normal population) but can be as high as 17% of women with reproductive disorders shown at the clinics. This chapter covers the prolactin production and immunology, heterogeneous forms, practical guide in infertility pathophysiology, management, clinical diagnosis, and treatment. Prolactin-secreting pituitary tumors are the common cause of amenorrhea and infertility in premenopausal women. The goals of therapy are to normalize prolactin, restore gonadal function and fertility, and reduce tumor size. Dopamine agonists are the preferred therapy.