We determined the clinical value of routine transthoracic echocardiography performed after catheter ablation of supraventricular tachyarrhythmias in children. Between April 1996 and December 2003, 253 children, of whom 135 male, with the overall group having a median age of 9, ranging from 0.1 to 19 years, underwent 280 uncomplicated radiofrequency catheter ablation procedures for supraventricular tachyarrhythmias at three institutions. In every child, transthoracic Doppler echocardiography was performed before and after the procedure. The pre-ablation transthoracic echocardiograms were normal in all, and this was one of the criterions for inclusion. The post-ablation echocardiogram showed a disorder in four asymptomatic patients. In one patient, with focal atrial tachycardia, ablated via a retrograde aortic approach, there was mild aortic valvar insufficiency. This had resolved 6 months later. Pericardial effusions developed in 3 other children. In 2 the effusions resolved spontaneously but 1 patient required pericardial drainage. This same patient also developed clinically asymptomatic mild aortic insufficiency, which resolved spontaneously within 6 months. Routine echocardiography after uncomplicated catheter ablation procedures is of clinical value, and is especially indicated when a retrograde aortic approach has been used.