The results of percutaneous mitral valvulotomy by the Double Balloon and the Inoue Balloon were compared in 100 patients referred to Marie-Lannelongue Hospital between 7/11/86 and 8/3/91, paired for age, sex and echocardiographic features of the mitral valve. The transvalvular diastolic pressure gradient at catheterisation or Doppler echocardiography decreased significantly and similarly with the two techniques: -65 +/- 19% versus -64 +/- 15% (p = 0.10) and -66 +/- 22% versus -58 +/- 23% (p = 0.20) for the Double-Balloon and the Inoue Balloon techniques respectively. Similarly, the mitral valve surface area measured by planimetry during echocardiography or calculated from the Gorlin formula increased by 0.9 +/- 0.39 cm2 with the Double Balloon and by 0.88 +/- 0.32 cm2 with the Inoué Balloon (p = 0.91) or by 0.98 +/- 0.62 cm2 versus 0.87 +/- 0.45 cm2 (p = 0.42). The number of commissures opened was the same with both techniques. The evolution of mitral regurgitation after dilatation was similar: stable or less severe in 61% dilated by the Double Balloon and 68% by the Inoue Balloon; aggravation by more than one grade in 7 and 5% respectively (p = 0.17). Complications were rare and comparable with both techniques. The results with the two methods were the same if patients with an optimal indication and those with more severe mitral valve disease were considered separately. The rapidity and simplicity of percutaneous mitral valvulotomy with the Inoué Balloon make it the technique of choice.