Ten consecutive patients with subarachnoid hemorrhage (SAH) of unknown cause were examined for sellar abnormalities and pituitary dysfunction. The diagnosis of SAH rested on a typical history and the demonstration of blood in the cerebrospinal fluid (computed tomography (CT), lumbar puncture). Initial CT and four-vessel angiography were performed in all patients, and five had repeat angiography. Endocrinological assessment was done after the initial angiography, and abnormal findings from this first study were reassessed 3 months later. The follow-up study included a high resolution CT scan of the sellar region. One patient had panhypopituitarism. Insufficient growth hormone secretion alone or combined with a low plasma concentration of estradiol or testosterone was found in another seven patients. The sella was ballooned or enlarged in three patients, and four patients had at follow-up a partly empty sella. A spontaneous development of a partly empty sella from an adenoma with suprasellar extension was observed in the patient with panhypopituitarism. This patient had experienced pituitary apoplexy with resulting SAH. Based on sellar enlargement, an empty sella, and pituitary dysfunction, this pathogenesis was suggested in another three patients. Our findings suggest that hemorrhagic necrosis in a pituitary adenoma may be an important cause of SAH with normal angiography.