Transesophageal echocardiography (TEE) is a valuable technique to assess mitral valve anatomy and the mechanism of mitral regurgitation (MR). We present the case of a 35-year-old woman with severe MR due to restrictive motion of the posterior mitral leaflet, who was referred for mitral annuloplasty. Under physiologic circumstances, a severe (grade 3+) MR was present, whereas in the operating room during general anesthesia, the MR had disappeared almost completely. The downgrading of MR due to general anesthesia and the associated mechanisms of this phenomenon are discussed in this case.