The purpose of this study was to assess the relation between myocardial metaiodobenzylguanidine (MIBG) uptake and left ventricular systolic and diastolic functional parameters, both of which are known as predictors of prognosis in patients with dilated cardiomyopathy. Echocardiography and iodine-123-MIBG myocardial scintigraphy were performed in 35 patients of dilated cardiomyopathy with normal sinus rhythm. Mean myocardial MIBG uptake in the patient group at early and delayed images were significantly lower than those in normal control subjects (10.6 ± 1.1, 9.8 ± 1.2 vs 12.4 ± 1.0, 12.1 ± 1.0, p < 0.01). There were, however, no significant differences of mean MIBG uptake in the lung and mediastinum between the two groups (p > 0.05). There were no significant correlations between myocardial MIBG uptake, expressed as the ratio of heart/mediastinum MIBG activity at delayed image, and left ventricular systolic and diastolic functional parameters ?left ventricular ejection fraction, left ventricular end-diastolic dimension, peak velocity of early diastolic filling (E velocity), deceleration time of E wave, cardiac output, left ventricular end-diastolic pressure?. In conclusion, the myocardial uptake of MIBG is decreased in patients with dilated cardiomyopathy assessed by iodine-123-MIBG myocardial scintigraphy. There were, however, no significant correlations between myocardial MIBG uptake and left ventricular systolic and diastolic functional parameters derived from echocardiography.