The diagnosis of acute mitral regurgitation (MR) is often missed or delayed because the clinical presentation is substantially different from that in patients with chronic MR. Management of acute MR depends on the specific aetiology of valve dysfunction and there is a lack of consensus on the optimal therapeutic approach in many patients. In particular, management of secondary MR due to acute ischaemia is challenging because of unique mechanisms of valve incompetence compared with chronic ischaemic MR. Another clinical challenge is management of acute MR due to transient systolic anterior motion of the mitral valve in the acute phase of Takotsubo cardiomyopathy, which commonly resolves within a few weeks. Additionally, iatrogenic MR induced by intraventricular devices is a recently recognised aetiology of acute MR. Acute primary MR typically requires early surgical intervention, for example, with a flail leaflet or endocarditis, because of acute cardiovascular decompensation with an abrupt increase in left atrial pressure. In an emergency situation and high surgical risk, a percutaneous mitral valve edge-to-edge repair is an alternative therapeutic option. Firm diagnosis of the severity and aetiology of acute MR is necessary for proper decision making, including timing and types of surgical intervention.