Introduction: Mitral regurgitation (MR) is characterized by systolic blood flow reversal from the left ventricle to the left atrium. A 2019 study indicated that in the USA, clinically significant MR (sMR) is associated with a substantial healthcare cost burden. In Taiwan, few data are available to describe the clinical characteristics, treatment patterns, and economic burden of patients with sMR. Methods: Using the National Health Insurance Research Database (NHIRD), a national, detailed claims database of all 23 million residents of Taiwan, we conducted a retrospective cohort study to identify patients with sMR and quantify the impact of the disease on Taiwan's healthcare system. We classified patients with sMR into three cohorts based on disease etiology: functional MR (sFMR), degenerative MR (sDMR), and uncharacterized MR (sUMR).