SummaryThe purpose of this work was to study the hemodynamic characteristics of 10 cases of mitral stenosis.All presented a sometimes important increase in the systolic pressure in the right ventricule, in the pulmonary and also capillary pulmonary pressure.In three cases the pressure in the right auricule was also raised. The gra- diant between the pressure in the pulmonary artery and the pressure in the pulmonary capillaries was generally low. The resistance in the small pulmonary arteries was low in 3 cases, high in 4 cases and very high in 1 case.The mitral valve had a surface, calculated from the Gorlin’s formula, of 2 cm2and 2,4 cm2in two subjects, and the figures varied from 0,9 to 1,6 cm2in six other subjects. In 4 patients, these figures were checked during the operation.