The results of anatomical examination in fifty patients aged from 50 to 69 years presenting with calcified and tight aortic stenosis are reported. The calcifications were located mostly on the aortic side of the valves, and the aortic orifice area was less than 1 cm2. The macroscopic features of the aortic valve system fell into three categories: bicuspid valve in 28 patients (21 men, 7 women), trivalve orifice with commissural adhesion (calcified in every case) in 21 patients (18 men, 3 women), and trivalve orifice without commissural adhesion in 1 patient (a 68-year old man). Male predominance was obvious (40/50; 80 p. cent). From an analysis of the various anatomical data recorded three differences emerged: the aortic annulus was wider in cases with bicuspid valve (P less than 0.01); the calcifications did not involve the free border of the valves in cases with bicuspid valve or trivalve orifice without commissural adhesion, but they involved this free border in 1 out of 2 cases with trivalve orifice and commissural adhesion; the aortic stenosis was minimal to moderate in all cases with trivalve orifice and commissural adhesion. In patients of that age group, the main cause of stenosis was bicuspid valve which seemed to be congenital in all cases. Dilatation with the finger through the left ventricle - which cannot by any means be assimilated to inflation of a balloon passed into the aortic orifice - resulted in significant opening of the aortic orifice by compression and/or disruption of the calcareous formations in patients with bicuspid valve.(ABSTRACT TRUNCATED AT 250 WORDS)