AIMThe aim of this study is to elucidate the prevalence, incidence, patient characteristics, and recent treatment trends of valvular heart disease (VHD) in Japan using a comprehensive claims database.METHODSWe conducted a cross-sectional study using the national database of health insurance claims in Japan (April 2009-June 2021), which contains data from the entire Japanese population, regardless of the type of medical facility. Descriptive analyses were conducted to examine the prevalence, incidence, and patient characteristics of each valve disease in 2020 based on diagnoses, and the treatment trends from 2009 to 2021.RESULTSWe identified 28,366,924 patients with VHD over the entire data period, and 2,473,070 patients in 2020, including 711,876 newly diagnosed. The prevalence and annual incidence in the entire Japanese population were 1.96% (1.88% in men and 2.04% in women) and 0.56% (0.53 and 0.60%), respectively, and increased with age in adults. Among the 8 types of VHD in combination with a disordered valve (aortic, mitral, tricuspid, or pulmonic) and type of valve disease (stenosis or regurgitation), mitral regurgitation had the highest prevalence followed by aortic regurgitation and tricuspid regurgitation. Heart failure was diagnosed in ≥50% of patients with aortic, mitral, or tricuspid disease, with the highest rate in mitral stenosis. The number of open-heart surgeries remained constant, while the number of transcatheter surgeries increased over time, particularly between 2016 and 2021. Aortic stenosis prevalence in transcatheter surgeries rose to ≥60% in 2014 and ≥80% in 2016.LIMITATIONSDiagnoses of VHD and comorbidity were based on claims data, so diagnostic criteria and disease severity are unknown, and misclassification of VHD types might have occurred. Incidence rates were based on the initial VHD diagnosis only, excluding any subsequent diagnoses of different VHD type. Conclusions: We presented basic information, which may provide an understanding of the clinical status of VHD in Japan.