Open heart mitral commissurotomy was performed in 85 patients between January 1973 and January 1976. This series comprised 38 patients with pure mitral stenosis and 47 patients with associated mitral and aortic or tricuspid lesions. Mitral commissurotomy, always complete, was associated with correction of mitral incompetence, either preexisting or peroperative, in 19 cases; in 44 cases with correction of an aortic lesion and in 10 cases with correction of a tricuspid lesion. The surgical mortality was 2.3 p. 100 (2 deaths); one post-operative myocardial infarction and one spontaneously regressive post-operative jaudice was observed. No cases of post-operative systemic embolism was observed. A short apical systolic murmur was detected in 12 cases. The results of this series together with those already published suggest that the indications of this operation should be widened and that it should be employed whenever the best immediate anatomical result and long-term prognosis are desired.