BACKGROUND The objective of this study is to evaluate the immediate result of the percutaneous mitral valvotomy in patients with previous surgical mitral commissurotomy, compared with patients considered ideal for the performance of the procedure. METHODS The authors of this paper compared the immediate results of the percutaneous mitral valvotomy (PMV) performed on two groups of patients. Group I included 20 patients who were good candidates for PMV, with an echocardiographic score of < or = 8, without evidence of left atrial thrombus, and with no recent embolic event. Group II included seven patients with previous mitral commissurotomy (MC). RESULTS According to the Wilcoxon non-parametric t test analysis, the hemodynamic variables changed significantly in the patients of group I: the mitral area increased from 1.21 +/- 0.41 to 2.62 +/- 0.75 cm2 (P = < 0.001); the mean left atrial pressure decreased from 17.2 +/- 7.2 mmHg to 9.2 +/- 4.5 mmHg (P = < 0.001), and the pressure transmitral gradient decreased 12.4 +/- 6.8 to 3.3 +/- 1.26 mmHg (P = < 0.001). No statistically significant difference in the hemodynamic changes of the patients of group II after the PMV was found: the mitral area increased from 1.2 +/- 0.2353 to 1.96 +/- 0.57 cm2; the mean left atrial pressure decreased from 17.42 +/- 10.35 to 12.42 +/- 7.3 mmHg, and the pressure mitral gradient decreased from 11.47 +/- 6.5 to 5.7 +/- 4.8 mmHg. The mitral area determined by echocardiographic procedure showed the same tendency in patients with previous MC. CONCLUSIONS In spite of this tendency, during the follow-up after PMV the NYHA functional class decreased from II-IV to I in the patients with previous MC. Because a second surgical MC results in higher mortality, PMV is indicated in patients with previous MC, delaying or avoiding a second MC or valve replacement.