Surgical treatment strategy of functional mitral regurgitation (FMR) is still controversy. This is probably because FMR is not a valvular disease, but a ventricular disease. According to the results of CTS Net trial, AHA/ACC guideline was revised in 2017. In moderate ischemic MR, MR recurrence was significantly reduced when mitral valve plasty (MVP) was performed in addition to CABG, but there was no difference in survival. Due to this unclearness of the effect of MVP, MVP was classified to class IIb. In severe ischemic MR, mitral valve replacement (MVR) was classified to class IIa, because MR recurrence was significantly higher in MVP than MVR. However, there was no significant survivial difference between MVP and MVR, on the contrary MVP without MR recurrence showed better LV reverse re-modeling than MVR. The limitation in both of these trials was that most of the MVP was only simple reduction annuloplasty (RMAP) and any sub-valvular procedure, which is expected to be more effective to treat FMR, was not applied. MVP is not equal to RMAP, so that the real effectiveness of MVP including sub-valvular procedure is misunderstood and the interpretation of the results of CTS Net trial might be misleading. In this session, in the view point of tethering mechanism of FMR, we would like to discuss about not only surgical indication of FMR but also each procedural effectiveness and limitation.