To investigate the change of the left atrial volume before and after the percutanous balloon mitral valvuloplasty(PBMV),the 3-D reconstruction of the left atrium volume gas performed in 16 patients.The left atrial volume was 135.76±54.25cm3in diastole and 83.26±31.79cm3in systole before the PBMV and 89.34±46.55m3in diastole and 55.43±18.84m3in systole after PBMV.The change of the left atrial volume before and after PBMV was significant.No significant correlation existed between left atrial volume and the left atrial pressure,left atrial volume and pulmonary artery pressure both before and after PBMV.