The prevalence of conduction defects was investigated in 51 patients older than 60 years with aortic stenosis (AS) who underwent aortic valve replacement. Thirty one of the 51 patients, (61%) had associated mitral anular calcium (MAC). The mean age and prevalence of coronary artery disease, systemic hypertension and diabetes mellitus were similar in both groups. The prevalence of conduction defects (atrioventricular block, sinoatrial disease, bundle branch block, left anterior hemiblock or intraventricular conduction defect) was 18 of 31 (58%) in patients with MAC and 5 of 20 (25%) in patients without MAC (p less than 0.025). We conclude that patients older than 60 years with AS have a high prevalence of MAC, and that the prevalence of conduction defects is higher in patients older than 60 years with combined AS and MAC than in patients with AS without MAC.