A 49-yr-old woman presented with an extensive prolactinoma (serum PRL > 10,000 mU/L, normal range < 450 mU/L). Over a 5-yr period following transsphenoidal surgery and pituitary irradiation, she became increasingly resistant to high doses of bromocriptine and underwent transfrontal surgery followed by stereotactic radiotherapy. In spite of these treatments, serum prolactin estimations rose progressively to > 100,000 mU/L. Magnetic resonance imaging scanning demonstrated a massive cystic tumor invading the temporal lobes, extending into the cervical and thoracic spine, with metastases to cervical lymph nodes. High-dose cabergoline administration resulted in a 30% decrease in serum PRL. Octreotide was administered as a continuous sc infusion with a profound analgesic effect on facial pain but with no effect on tumor progression. She was treated with a course of chemotherapy consisting of carboplatin and etoposide without any noticeable effect. The patient died 6 months following chemotherapy. Immunocytochemical analysis demonstrated positive nuclear staining for WAF-1, Rb protein, c-myc, and p53 both in the original and metastatic tumors. The metastases but not the primary tumor stained for c-jun. Metastatic prolactinoma remains a therapeutic challenge. It is associated with a variable proto-oncogene expression, which may be coincidental or causal. Cabergoline had no advantage over bromocriptine. Octreotide relieved facial pain but did not alter tumor progression. An effective therapy for metastatic prolactinoma remains to be identified.