To obtain epidemiologic information on submitral calcium, 2,069 subjects in the original Framingham Study cohort (mean age 70 +/- 7 years) and 3,625 of the offspring of the cohort and their spouses (mean age 44 +/- 10 years) with adequate echocardiograms were evaluated. Submitral calcium was detected in 162 (2.8%) of the 5,694 subjects; greater than 90% of the subjects with such calcium came from the 40% of the study group greater than 59 years of age. Women were more than twice as likely to have such calcium as men. Age in both sexes, systolic blood pressure in men, and obesity in women were significantly and independently associated with submitral calcium. There was a 12-fold excess of atrial fibrillation in subjects with (20 of 162, 12%) compared with those without (53 of 5,532, 1%) submitral calcium.