The incidence, the size of mitral ring calcification (MRC) and its relation to the mitral valve disease were examined in a total of 600 consecutive autopsy cases of over 60 years of age. (1) The incidence of MRC was 10% (60 cases among 600), and the sex difference was statistically significant with 6.7% in male and 13.3% in female (p<0.01). The age was 82 years in average, and an increase of its incidence with aging was significant only in female (p<0.005). (2) MRC was found in the annulus of the posterior mitral leaflet. The length of MRC was 12.5±10.3mm in male, and 31.8±23.5mm in female (p<0.01). Large MRC more than 30mm were found in 1 man and 19 women. (3) The relationship between the length and cross sectional diameter of the MRC showed a positive correlation (r=0.75). Three cases of mitral stenosis or combined stenosis and regurgitation belonged to the extremely large MRC group. (4) There were 27 cases with systolic murmur; 3 holosystolic and 24 ejection type. In large and small MRC groups, systolic murmurs were found in 70% and 33% (p<0.05), MRC extending to the anterior leaflet in 65% and 2.5% (p<0.005), moderate to severe calci-fication of the aortic valve in 40% and 20% (n.s.), respectively. (5) Xray films were examined retrospectively, and large MRC was diagnosed in 85%, and incidence of calcification in the other soft tissues (trachea, bronchi, costal cartilage, aortic arch, thoracic and abdominal aorta) was higher in large MRC group than in the control group (87 cases) without MRC (p<0.005).