Abstract Background Myocardial biopsy is an essential procedure for the diagnosis of myocarditis and cardiomyopathy. As specific treatment for secondary cardiomyopathies becomes available, EMB becoming increasingly important. Although the procedure can be performed safely at institutions familiar with the procedure, some institutions tend to hesitate to perform EMB because of procedural complications. In addition, complete right bundle branch block (CRBBB) is a complication of right ventricular biopsy (RV-EMB) that occurs at a certain rate. Therefore, Patient with complete left bundle branch block (CLBBB) often exibit reluctance to undergo RV-EMB due to the risk of complete atrioventricular block. Although there are two approaches to RV-EMB, transfemoral vein and trans-intracavitary vein, and each institution is familiar with its approach, no study has ever looked at the difference in complication rates, mainly complete right bundle branch block, due to the different approach sites for right ventricular biopsy. Aims This study aims to examine the differences in complication rates, mainly CRBBB, due to differences in the approach site of the RV-EMB procedure. Methods/Results The subjects were 338 consecutive patients who underwent RV-EMB at our hospital between January 2017 and December 2022. We performed a retrospective analysis of 274 cases, excluding 43 cases that were originally CRBBB and 21 cases with ventricular pacing, ventricular fibrillation (VF), complete atrioventricular block from beginning to end, and no pre- and post-ECGs. The transfemoral venous approach group (Group TF) included 96 cases and the transjugular venous approach (Group TJ) included 178 cases, with Group TF using more warfarin (13.5% vs. 3.4%, p=0.004) and obtaining fewer specimens compared to Group TJ (3.0±1.0 vs. 3.8±0.6 pieces, p<0.001). Transient CRBBB was present in 28 (29.2%) patients in Group TF and 12 (6.7%) patients in Group TJ (p<0.001); CRBBB persisted beyond 24 hours in 8 (8.3%) and 2 (1.1%) patients, respectively. There was one case of cardiac tamponade in Group TF and two cases of VF in Group TJ, but no cases of stroke, permanent pacemaker implantation, or death. Multivariate logistic regression analysis showed that the transfemoral approach and corticosteroid administration emerged as independent predictor in the occurrence of CRBBB (p<0.001, odds ratio 0.17 and p=0.021, odds ratio 3.76, respectively.), whereas in cases of sustained CRBBB, solely the transfemoral approach stood as an independent predictor (p=0.002, odds ratio 0.07). Conclusions In RV-EMB, the transjugular venous approach has the potential to decrease CRBBB as a complication. The transjugular vein approach may be preferable in cases where complete AV block is a concern, such as patients who originally have CLBBB.