A patient with mid-gut carcinoid tumor and the unusual complication of retroperitoneal fibrosis was also found to have a prolactinoma. This case brings the number of reported mid-gut carcinoid tumors complicated by a second endocrine neoplasm to five. Three of the second tumors were parathyroid in origin, and the fourth was an insulinoma. In view of the rarity of second tumors and in the absence of documented familial occurrence, it is inappropriate to exhaustively study each person with mid-gut carcinoid tumor, or their families, for a second endocrine neoplasm; however, physicians caring for patients with mid-gut carcinoid should be aware that second tumors are possible. Retroperitoneal fibrosis is also a rare complication of carcinoid, but can be associated with renal failure that can be prevented by surgical intervention. Thus, physicians caring for patients with the carcinoid syndrome should also be aware of this complication.