Objective: TSH-secreting pituitary adenomas (TSH-omas) are a rare cause of thyrotoxicosis. First-line therapy for these tumours is neurosurgery, although medical therapy with somatostatin analogues (SSAs) is increasingly used for this indication. Design: and patients We retrospectively reviewed the data of patients with a TSH-oma (n = 18, 67% males) followed between 1989 and 2011 (median follow-up 7 years, range 1-21) in three academic medical centres in the Netherlands, focusing on the role of SSA treatment. Measurements: Patient records were reviewed for clinical, biochemical, imaging, pathological and treatment characteristics. Results: At initial evaluation, biochemical hyperthyroidism with non-suppressed TSH concentrations was detected in 94% of the patients. The majority of patients (72%) had a macroadenoma with extrasellar extension. Fourteen patients underwent surgery, resulting in postoperative euthyroidism in six patients (43%). Recurrence of hyperthyroidism developed in three of them after 5, 24 and 32 months, respectively. Adjuvant radiotherapy (n = 2) did not induce remission. Three patients received SSA therapy exclusively, resulting in apparent cure in one of them. During long-term follow-up, 72% of all patients required medical therapy (mostly SSA treatment). Euthyroidism was achieved in all but one patient, who refused all treatments. Conclusions: Our results demonstrate that patients with TSH-omas, who often present with large macroadenomas with extrasellar extension, have an excellent response to SSA therapy. Because the results of surgery and radiotherapy are disappointing, primary medical therapy may be considered in virtually all patients, except in case of optic chiasm compression, especially in those harbouring large adenomas with parasellar extension. © 2013 John Wiley & Sons Ltd.