The rather widely held belief that systemic arterial hypertension is a major factor either in the genesis of saccular aneurysms or in their subsequent rupture is questioned on the basis of our clinical and pathological analysis of 250 patients with aneurysms. Analysis of 150 patients with ruptured and 100 patients with unruptured saccular aneurysms for clinical and morphologic evidence of hypertension revealed no notable excess over an age- and sex-matched control autopsy population. There is no evident association of hypertension with multiplicity of aneurysms, the age at which aneurysms present clinically, or with their rupture. All available data clearly indicate that saccular aneurysms can arise in the absence of fixed arterial hypertension and that they can also rupture in the absence of fixed hypertension.