OBJECTIVE--To assess the outcome of percutaneous balloon dilatation of the mitral valve in critically ill young patients with intractable heart failure. DESIGN--Retrospective analysis of all such patients presenting over a period of 4 years. PATIENTS--Of 432 consecutive patients undergoing percutaneous balloon dilatation of the mitral valve, 12 (mean age 29 years) with intractable heart failure were identified. Nine had severe pulmonary oedema and three had pulmonary oedema with severe right heart failure and hypotension. Three patients were pregnant and three required mechanical; ventilatory support. PROCEDURE--Percutaneous balloon dilatation of the mitral valve was performed using the Inoue balloon technique. The procedure was shortened by excluding full right study, cardiac output measurement, and left ventriculography. The mitral valve morphology and mitral valve area were determined before and after percutaneous balloon dilatation using cross sectional Doppler echocardiography. RESULTS--The procedure was technically successful in all patients. The mean (SD) echocardiographic value of the mitral valve area increased from 0.7 (0.1) to 1.4 (0.2) cm2 with a concomitant reduction in pulmonary artery systolic pressure (Doppler) from 81 (17) to 50 (7) mm Hg. There was a significant clinical improvement in all patients. The mean (range) fluoroscopy time for the procedure was 6.9 (1.7-14.1) min. During follow up (mean 10 months) nine patients were in New York Heart Association (NYHA) functional class I, one was in class II, one under NYHA elective mitral valve replacement, and one, who refused elective surgery, died suddenly at home. CONCLUSION--Percutaneous balloon dilatation of the mitral valve can be performed as a life saving procedure in critically ill patients with mitral stenosis, as even a modest increase in valve area in these patients produces gratifying clinical improvement.