Objective: The purpose of this study was to compare delayed enhancement (DE) cardiac magnetic resonance (MR) imaging with the indine-123-metaiodobenzylguanidine(123I-MIBG) scintigram for measurement of left ventricular (LV) contraction function in patients with dilated cardiomyopathy (DCM). Materials and methods: DCM patients (n=29: mean age,51.9years; seven women) were evaluated by both DE cardiac MR imaging and 123I-MIBG scintigram. In all patients biopsy specimen showed disarray of the myocardium that was consistent with DCM. DE cardiac MR images were acquired using a two-dimensional segmented inversion-recovery prepared gradient-echo sequence (TI=250msec) 15minutes after intravenous administration of 0.1 mmol/kg gadolinium.The average CNR per slice (aCNR) for the LV myocardium was calculated.123I-MIBG scintigram was acquired at 15minutes and 3 hours (delayed imaging) after intravenous administration of 123I-MIBG (111MBq). The heart-to-mediastinum radioactivity ratio (H/M ratio) and washout rate (WR) was calculated. We evaluated the relationships between aCNR, WR, delayed H/M ratio, and the contraction function of the LV. Results: In MR imaging, mean aCNR was significantly higher in the low LV ejection fraction (LVEF<25%) group (n=11, 6.6±3.6) than in the high LVEF (≥25%) group (n=18, 2.4±2.9). However, with the 123I-MIBG scintigram, delayed H/M and WR were not significantly different between high (delayed H/M ratio ; 1.7±0.3, WR; 37.6±14.5) and low (delayed H/M ratio; 1.7±0.2, WR; 38.2±14.2) LVEF groups. Conclusions: DE MR imaging reflects the contraction function of the LV in patients with DCM, which may be related with myocardial fibrosis. DE MR imaging may be more useful to evaluate the contraction function of LV than 123I-MIBG scintigram.