One hundred eighteen consecutive cases of spontaneous subarachnoid hemorrhage seen at one hospital during a 3-year period were examined to assess the prevalence of hypertension and the correlation between the presence of hypertension and the risk of early death. Eighty-seven of the patients had intracerebral aneurysms. The diagnosis of hypertension was determined by means of three complementary criteria: a history of treatment with antihypertensive drugs; systolic and/or diastolic blood pressure levels > or = 160 and 95 mm Hg, respectively, measured by the general practitioners of the patients before the onset of the subarachnoid hemorrhage; and the presence of left ventricular hypertrophy determined by echocardiography and/or necropsy. The major findings were as follows: 1) hypertension was present in at least 41% of the patients; 2) in 37% of 51 patients with no history of hypertension before the hemorrhage, left ventricular hypertrophy was diagnosed; and 3) the frequency of hypertension and left ventricular hypertrophy was significantly higher in patients who died within 14 days after the bleeding episode compared with patients surviving this period.