Abstract Backgrounds and Objectives Recognizing the natural progression of the aortic valve (AV) disease is helpful in planning the intervention of significant rheumatic mitral valve (MV) disease accompanying rheumatic AV disease. We aimed to investigate the long-term course of AV disease and the need for AV surgery in patients with rheumatic mitral valve disease who underwent MV intervention. Methods We retrospectively investigated the progression of AV disease with rheumatic changes following MV intervention in a single tertiary center. A total of 890 patients who underwent MV intervention for rheumatic MS or mitral regurgitation (MR) without concurrent AV intervention were initially screened for eligibility. Among them, 76 patients met the criteria for rheumatic etiology and had over a year of echocardiographic follow-up after MV intervention (64 surgery, 12 balloon valvuloplasty). Results The median follow-up period was 4 years (mean 5.8 years, ranging from 1 to 31 years). MS was the most common indication for mitral intervention. Overall, trans-aortic peak velocity (AV Vmax) changed from 2.2 ± 0.6 m/s to 2.4 ± 0.8 m/s, and mean pressure gradient (mean PG) changed from 11.1 ± 6.0 mmHg to 13.2 ± 8.2 mmHg. Six patients fell under severe aortic stenosis (AS) definition-wisely (Figure 1) and three of them were classified as low flow low gradient severe AS despite normal ejection fraction. Eventually, four patients were found to have true-severe AS and only one of them underwent AV surgery for severe AS per se. None of the patients with aortic regurgitation deteriorated to severe (Figure 2). Conclusions Only a small portion of rheumatic AV involvement progresses to severe AS after MV intervention, and performing MV intervention for severe mitral stenosis or mitral regurgitation in patients with concurrent mild or moderate AS or aortic regurgitation due to rheumatic changes might be reasonable.The changes in the grading of ASThe changes in the grading of AR