The purpose of this study is to determine the value of 123I-MIBG scintigraphy to evaluate cardiotoxic effects of antineoplastic agents. We performed 123I-MIBG scintigraphy in 19 patients with malignant neoplasms treated with multiagent chemotherapy including adriamycin. Based on the initial and delayed myocardial images (planar and SPECT), segmental myocardial uptake and wash-out ratio of MIBG were obtained. Low uptake in the myocardium and rapid wash-out from the myocardium especially in the lateral and inferior segments, were noted in patients with cardiotoxicity. Such cardiotoxic effect is dose-dependent. This abnormal areas corresponded to decreased glucose metabolism observed by 18F-FDG PET images. This was suggestive of mitochondrial dysfunction or myocardial damage. There was mismatch in the defect when compared to the result of 201Tl perfusion scintigraphy, and LVEF obtained failed to demonstrate abnormalities. Therefore, 123I-MIBG scintigraphy may be an useful measure in detecting cardiotoxicity related to antineoplastic agents in early stage.