Our experience from 1968 to 1985 in 12 women requiring closed mitral valvotomy during pregnancy is reviewed. All patients had severe mitral stenosis and were in functional class 3 (2 patients) or class 4 (10 patients). Mitral valvotomy was performed between the 18th and the 30th week of pregnancy using a transventricular dilator. Improvement in functional class was noted in all patients postoperatively. One patient had postvalvotomy mitral regurgitation and heart failure, which responded to diuretics; the subsequent course was uneventful. Eleven patients had normal deliveries; whilst one patient had a Caesarean section for an obstetric indication. All babies were normal and there was no maternal death. This series confirms that closed mitral valvotomy can be performed with an acceptable degree of safety during pregnancy, when indicated.