PURPOSE: To evaluate the usefulness of cardiac MRI in the diagnosis of clinically suspected arrhythmogenic right ventricular dysplasia (ARVD). MATERIALS AND METHODS: Between February 1991 and January 1999, 15 patients [M:F=13:2, aged 2 -60 (mean, 37 -7) years] with clinically suspected ventricular arrhythmia due to unknown causes underwent MR imaging. Using a CP body array coil and the single slice breath hold technique, ECG-gated T1-weighted images were obtained. In all patients, these were acquired transaxially from the diaphragm to the aortic arch and along the true short and long axis, and in two, coronal images were obtained. On the basis of clinical and MRI diagnostic criteria, ARVD was classified as one of four types. The significance of differences in diagnostic grades between clinical and MRI criteria was determined using Wilcoxon's signed rank test. RESULTS: According to both clinical and MRI criteria, it was highly probable that three of the 15 patients had ARVD. In eleven, both sets of criteria indicated the same diagnostic grade. Wilcoxon's signed rank test indicated no significant differences in diagnostic grades between clinical and MRI criteria (p > 0.05). CONCLUSION: For the diagnosis or exclusion of ARVD, MR imaging is a useful modality.