Background: Right ventricular (RV) function is an important prognostic indicator. The acute effects of cardiac interventions or cardiac surgery on global and longitudinal RV function are not entirely understood. In this study, acute changes of RV function during mitral valve surgery (MVS), percutaneous mitral valve repair (PMVR) and off-pump coronary artery bypass surgery (OPCAB) were investigated employing 3D echocardiography. Methods: Twenty patients scheduled for MVS, 23 patients scheduled for PMVR and 25 patients scheduled for OPCAB were included retrospectively if patients had received 3D transesophageal echocardiography before and immediately after MVS, PMVR or OPCAB, respectively. RV global and longitudinal function was assessed using a 3D multiparameter set consisting of global right ventricular ejection fraction (RVEF), tricuspid annular plane systolic excursion (TAPSE), longitudinal contribution to RVEF (RVEFlong) and free wall longitudinal strain (FWLS). Results: Longitudinal RV function was significantly depressed immediately after MVS, as reflected by all parameters (RVEFlong: 20 ± 5% vs. 13 ± 6%, p < 0.001, TAPSE: 13.1 ± 5.1 mm vs. 11.0 ± 3.5 mm, p = 0.04 and FWLS: -20.1 ± 7.1% vs. -15.4 ± 5.1%, p < 0.001, respectively). The global RVEF was slightly impaired, but the difference did not reach significance (37 ± 13% vs. 32 ± 9%, p = 0.15). In the PMVR group, both global and longitudinal RV function parameters were unaltered, whereas the OPCAB group showed a slight reduction of RVEFlong only (18 ± 7% vs. 14 ± 5%, p < 0.01). RVEFlong yielded moderate case-to-case but good overall reproducibility. Conclusions: TAPSE, FWLS and RVEFlong reflect the depression of longitudinal compared to global RV function initially after MVS. PMVR alone had no impact, while OPCAB had a slight impact on longitudinal RV function. The prognostic implications of these phenomena remain unclear and require further investigation.