['An association between mitral valvar prolapse and low body mass index has been proposed. The goal of this study was to evaluate this suggested association using two independent and large databases. For comparison, we evaluated the association, if any, between bicuspid aortic valve and low body mass index.', 'We retrospectively analyzed, using uni- and multivariate analysis, 1742 echocardiograms that were performed as a part of a cardiac screening of teenage athletes and 24,265 echocardiograms performed between 1984 and 1998 for various clinical indications.', 'The first database included a total of 12,926 (53%) female and 11,339 (47%) male patients. The second database included a total of 1172 male (67%) and 570 female (33%) high school athletes. Mitral valvar prolapse was independently associated with low body mass index in addition to mitral regurgitation in both data bases. An index less than 30 occurred in 78 of 13,874 (0.6%) as opposed to 7 of 3236 (0.2%) in the echo data base, p equal to 0.03, odds ratio: 2.4 confidence intervals: 1.1-5.2, and an index less than 20 occurred in 7 of 354 (2%) as opposed to 6 of 944 (0.6%) in the athletic data base, p equal to 0.03, odds ratio: 3.2 confidence intervals: 1.05-9.5. The finding of a bicuspid aortic valve did not have any association with low body mass index.'] Is mitral valvar prolapse significantly associated with low body mass index in addition to mitral and tricuspid regurgitation?