Presently, the standard of care for prolactinomas, a type of pituitary adenoma, is dopaminergic agents such as bromocriptine and cabergoline. However, dopaminergic agents may induce fibrosis of cardiac valves leading to valvular insufficiency, necessitating surgical treatment of prolactinoma. Fibrosis of prolactinoma can be induced by prolonged medical treatment with bromocriptine, and this usually occurs after years of treatment. In comparison to bromocriptine, there have been no reports of cabergoline-induced fibrosis of prolactinoma. There is a potential for greater emphasis to be placed on assessing the tumour consistency from preoperative MRI scans, or even preoperative contrast-enhanced 3D Fast Imaging Employing Steady-state Acquisition imaging to allow better planning of the surgery. We report a rare case of fibrosis of prolactinoma after cabergoline treatment resulting in its subsequent difficult surgical removal. This patient had early MRI changes of fibrosis of prolactinoma after a short period of 6 months of cabergoline treatment.