Our aim was to investigate the prevalence of the different causes of severe mitral regurgitation and the influence of gender on that prevalence. We performed a prospective study of 272 consecutive patients with severe mitral regurgitation that had been detected echocardiographically. Their mean age was 70.2 (13.8) years, and 143 were women (52.6%). Atrial fibrillation was present in 52.9%, 72.7% presented with heart failure, and 21.0% with previous myocardial infarction. The most common etiological factor was rheumatic disease (in 26.5%), with the etiology being unclear in 32 patients (11.8%). Rheumatic disease was more frequent in women, at 35.7%, than in men, at 16.3%, whereas other etiologies were less frequent in women (P< .001). In all age groups, a rheumatic etiology was more frequent in women. Rheumatic heart disease remains the main cause of severe mitral regurgitation observed in women referred to hospitals similar to ours.