Impairment of left ventricular (LV) function has previously been reported in patients with systemic sclerosis (SScl). An intermittent vasospastic process in the myocardium may contribute to the development of myocardial dysfunction. Vasodilators may therefore be potentially useful in the treatment of cardiac dysfunction in patients with SScl. This study was designed to evaluate the long-term effects of captopril on the myocardial function of patients with SScl. Twenty-two patients with SScl (15 patients with diffuse scleroderma and 7 patients with CREST syndrome, i.e. calcinosis. Raynaud's phenomenon, oesophageal hypomotility, sclerodactyly, telangiectasia) were investigated by means of Doppler and echophonocardiography before and after treatment with captopril (1.3 mg kg-1 body weight d-1) for 11-15 months. There were no significant differences in heart rate, systolic and diastolic blood pressure, end-systolic blood pressure, total peripheral resistance or LV diameters before or after treatment. However, captopril treatment exerted significant effects on LV function: the pre-ejection period (PEP) and the ratio of pre-ejection period to LV ejection time decreased significantly (P less than 0.05). Mitral E-point septal separation decreased significantly (P less than 0.01), even after adjustment for LV end-diastolic diameter (P less than 0.01). The ejection fraction increased significantly (P less than 0.05), and the isovolumic relaxation time decreased (P less than 0.01). The left atrial emptying index increased (P less than 0.01). The Doppler peak late to early ventricular filling velocity decreased (P less than 0.05), and the isovolumic index was also reduced (P less than 0.05). We conclude that both systolic and diastolic LV function indices improved in patients with SScl after captopril treatment for a mean period of 1 year. The effects of captopril might be due to vasodilation of the myocardial vessels and/or a direct effect on the renin-angiotensin system of the heart.