After infancy, galactorrhea usually is medication-induced. The most common pathologic cause of galactorrhea is a pituitary tumor. Other causes include hypothalamic and pituitary stalk lesions, neurogenic stimulation, thyroid disorders, and chronic renal failure. Patients with the latter conditions may have irregular menses, infertility, and osteopenia or osteoporosis if they have associated hyperprolactinemia. Tests for pregnancy, serum prolactin level and serum thyroid-stimulating hormone level, and magnetic resonance imaging are important diagnostic tools that should be employed when clinically indicated. The underlying cause of galactorrhea should be treated when possible. The decision to treat patients with galactorrhea is based on the serum prolactin level, the severity of galactorrhea, and the patient's fertility desires. Dopamine agonists are the treatment of choice in most patients with hyperprolactinemic disorders. Bromocriptine is the preferred agent for treatment of hyperprolactin-induced anovulatory infertility. Although cabergoline is more effective and better tolerated than bromocriptine, it is more expensive, and treatment must be discontinued one month before conception is attempted. Surgical resection rarely is required for prolactinomas.