Three patients with rheumatic mitral stenosis were treated with percutaneous mitral valvotomy. A Brockenbrough catheter was advanced transseptally into the left atrium and then into the left ventricle over a long guide wire. An angle wire loop retriever was advanced through a 10 Fr straight catheter via the femoral artery into the left ventricle. The retriever was used to catch the flexible end of the long guide wire. This end of the long guide wire was then drawn out of the right femoral artery by the retriever through the straight catheter. The straight catheter was left in the descending aorta; the Brockenbrough catheter was removed and a 7 Fr balloon catheter was introduced percutaneously over the long guide wire through the femoral vein. This balloon catheter was used for interatrial septal dilatation and right femoral venous dilatation. In two patients this catheter was replaced over the long guide wire with a 9 Fr Schneider-Medintag Grüntzig catheter (3 X 12 mm diameter when inflated) and in the other by a Mansfield (18 mm diameter when inflated). The procedure was well tolerated in these three patients and there were no complications. Haemodynamic function improved, there was appreciable decrease in dyspnoea, and exercise tolerance was increased. This procedure has several advantages: the balloon is more easily positioned through the mitral valve; the stability of the balloon during inflation is improved by traction at both ends of the long guide wire; and there is the option of rapidly exchanging one balloon for a larger one over the long guide wire. This technique seems to be less arrhythmogenic and results in less blood loss because manual compression of the femoral vessels after the procedure is easier.