Hyperprolactinemia from a pituitary adenoma is a rare cause of erectile dysfunction. Men with erectile dysfunction who are found to have a low testosterone level should have a measurement of their prolactin level. Treatment consists of lowering the prolactin level by medication or surgery, or both. Bromocriptine, a dopamine agonist, is efficacious in lowering elevated prolactin levels and can simultaneously shrink these pituitary tumors. With large tumors, transphenoidal surgery may be used to debulk/remove the tumor. Post-treatment prolactin levels can be used to monitor the efficacy of treatment.