Although N-terminal pro-brain natriuretic peptide (NT-proBNP) is a useful screening test of impaired right ventricular (RV) function in conditions affecting the right-sided cardiac muscle, the role of NT-proBNP remains unclear in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). This study was designed to clarify the relation between the plasma NT-proBNP level and the RV function evaluated by cardiovascular magnetic resonance (CMR) imaging. We selected 56 patients with confirmed ARVC only when their blood specimens for NT-proBNP measurements were collected within 48 hours of a CMR scan. The NT-proBNP level was significantly higher in patients with RV dysfunction than in patients without RV dysfunction (median of 655.3 [interquartile range 556.4 to 870.0] vs 347.0 [interquartile range 308.0 to 456.2] pmol/L, p <0.001). The NT-proBNP levels were positively correlated with RV end-diastolic and end-systolic volume indices (r = 0.49 and 0.70, respectively) and negatively correlated with RV ejection fraction (r = −0.76, all p <0.001), which remained significant after adjustment for age, gender, and body mass index. The area under the receiver-operating characteristic curve for NT-proBNP was 0.91 (95% confidence interval 0.80 to 0.97, p <0.001). The cut-off value of NT-proBNP (458 pmol/L) was associated with sensitivity, specificity, and positive and negative predictive values of 91%, 89%, 67%, and 98%, respectively. In conclusion, NT-proBNP is a useful marker for the detection of RV dysfunction and associated with extent of RV dilatation and dysfunction determined by CMR in patients with ARVC.