Because of inconsistencies in the popular theories regarding calcific aortic stenosis, another explanation has been sought for this common form of valvular heart disease. The valve lesions encountered after fatal brucellosis closely resemble those in calcific aortic stenosis. A similar type of chronic aortic valve disease was recognized in nine patients who recovered from brucellosis. Calcific aortic stenosis is chiefly a disease of males, corresponding to the sex incidence of brucellosis. For these and other reasons it is proposed that calcific aortic stenosis is, in most cases, a sequel of brucellosis.