There are several reports of beneficial effects of ACE inhibitors in both primary and secondary pulmonary hypertension. However the effect of ACE inhibitors in mitral stenosis is not documented. The authors report three patients with severe mitral stenosis in whom surgery was delayed. They had initial symptomatic improvement with diuretics and sodium restriction, but had recurrence of their symptoms while on treatment. Enalapril not only relieved their symptoms in particular exertional dyspnoea and haemoptysis but prevented recurrence and improved their effort tolerance without causing excessive fall of blood pressure or impairment of renal function.