We describe an unusual case of bilateral breast cancer synchronous with pituitary macroprolactinoma in a young male. Up to date, only very few of such cases have been described worldwide and to our knowledge this is the first one in which both breast cancer and pituitary macroadenoma have been found together at the time of presentation. A 45-year-old male was diagnosed as having a pituitary macroprolactinoma and bilateral breast cancer on the basis of hypogonadism (testosterone 2.9 pmol/l) with very high levels of prolactin (33,100 U/l), typical neuroradiologic finding of a pituitary macroadenoma, marked bilateral gynecomastia with mammographic pattern highly suspected for cancer and subsequent hystological confirmation. Bilateral mastectomy was performed and medical therapy with bromocriptine 10 mg/day was started. After 2-year follow-up the patient is disease-free. Hormonal, neuroradiological and oncological patterns are all negative or markedly improved. We stress the importance of prolactin for its possible biological effects on breast cancer induction or growth. Moreover in any case of hyperprolactinemia we suggest a mammographic examination and, in the case of breast cancer, at least a baseline hormonal profile.