MIBG cardiac imaging is a non-invasive procedure of studying neuronal recapture of noradrenaline. In adult cardiomyopathy, abnormal results are observed earlier than the increase in circulating catecholamines and constitute a reliable prognostic indicator of the disease. The authors assessed this technique in children with severe cardiac dysfunction in whom the evaluation of ventricular pump function was of primordial importance for the therapeutic decision. Twenty-eight patients aged 3 months to 20 years (average 6.4 +/- 5.8 years) were included in the study. Twenty had hypokinetic dilated cardiomyopathies: with respect to the normal values in adults MIGBG uptake was reduced in all cases. This alteration was correlated with the severity of myocardial dysfunction assessed by echocardiography but is was without doubt the expression of another type of physiopathological process. No relationship was observed with the aetiology of the cardiomyopathy. Eight children had a single ventricle treated by cavopulmonary bypass in 7 cases and by pulmonary artery banding in the other case: MIBG imaging did not allow assessment of myocardial function in these patients probably because the cavopulmonary bypass denervated the heart and thereby changed MIBG uptake independently of the cardiac function. These preliminary results are encouraging and should lead to the adoption of MIBG imaging as one of the key investigations in the functional evaluation of childhood cardiomyopathy and perhaps as an important parameter in the decision of transplantation in this indication.