We have reviewed our initial experience with percutaneous mitral valvulotomy (PMV) in 29 consecutive patients with mitral stenosis using the Inoue mono-balloon technique. In all cases, the venous transeptal anterograde approach was used. Age was 49.5 +/- 12.5 years (range 21-78) and only 5 (17%) patients were male. Clinical status was as follows: 15 patients were in NYHA class II, 13 NYHA class III and one in NYHA class IV. Atrial fibrillation was present in 15 (52%) patients and 16 (55%) were on coumarin. An echocardiographic score was employed to assess mitral valve anatomy, parameters including degree of thickening, mobility, calcification and subvalvular involvement were scored independently from 1 to 4. The echocardiographic score so determined was 7.72 +/- 2.1 for the entire group. Ten patients presented mild (+) mitral regurgitation prior to PMV. The mean duration of PMV was 76.2 +/- 29.6 minutes. In only one patient an inadequate positioning of the balloon prevented dilatation of the valve whereas the remaining 28 patients had their valves successfully dilated. Mitral valve area, by means of both Gorlin and Doppler (pressure half time) methods, increased in all cases: from 0.95 +/- 0.17 cm2 to 1.92 +/- 0.31 cm2 (p less than 0.001) and from 0.97 +/- 0.22 to 1.84 +/- 0.33 cm2 (p less than 0.001), respectively. Mitral regurgitation increased angiographically in more than 1 degree only in 1 patient, but no other cardiac or vascular complication occurred. Thus, in our experience PMV with the Inoue mono-balloon catheter is a safe and effective method for dilating mitral valve stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)