Mitral and Aortic valve rings were enlarged in a 70-year-old female with tiny mitral annulus after mitral annuloplasty before. She had undergone aortic valve replacement with No. 21 SJM valve and Kay's annuloplasty 10 years previously. The reoperation was needed because of mitral stenosis and tricuspid regurgitation. We applied the Manouguian technique for the enlargement of the mitral annulus because it was too small to implant a prosthetic valve, even though the Aortic prosthetic valve was functioning well. As too tight a mitral annuloplasty may make the possibility of mitral stenosis real, we should make the annulus remain wide enough.