Objective: To assess frequency, symptoms and outcome of pituitary apoplexy (PA) among pituitary adenoma patients, to gain better insight into risk factors for bleeding into pituitary adenoma, and to estimate the sequelae of PA by means of a matched control group. Method: By reviewing charts of 574 patients with pituitary adenoma we analysed incidence, symptoms and outcome of PA, and potential risk factors for developing PA by means of a control group (patients with pituitary adenoma without PA). Results: 42 suffered from PA; all had macroadenomas. 30/217 male (14%) and 12/179 female (7%) macroadenoma patients, 32/194 patients with clinically non-functioning (16.5%) and 10/202 with clinically active (5.0%) macroadenoma were affected. Antithrombotic therapy predisposed patients to PA (p = 0.026), diabetes mellitus and hypertension did not (p = 1.00). Patients with PA and pituitary adenoma patients without PA had similar frequencies of hypopituitarism (45 vs. 48%, p > 0.05) and visual field defects (38 vs. 55%, p > 0.05), but ophthalmoplegia was significantly more common (76 vs. 5%, p < 0.001) in patients with PA. Nearly all patients were treated by surgery; most recovered from ophthalmoplegia whereas visual function improved only moderately. Endocrine outcome was worse in patients with PA compared to patients without PA. Conclusions: Male gender and characteristics of the adenoma itself (especially tumour size and tumour type) rather than patient's cardiovascular risk factors such as diabetes and hypertension seem to predispose to PA; antithrombotic therapy may also be important.