In a total of 30 operations the mitral valve was reconstructed in 18, the tricuspid valve in 11, and both AV-valves in one patient. The result of reconstruction was tested first in the open arrested heart by injection of crystalloid solution into the appropriate ventricle either through the reconstructed valve or one of the great arteries. Upon termination of cardiopulmonary bypass the valve function was examined in the beating heart by means of transesophageal contrast echocardiography (TEE). For visualization 0.5-1.0 cc of agitated Gelifundol was injected into the ventricle. In 22 patients open testing as well as echocardiographic visualization showed identical and good operative results. In 6 patients TEE revealed mild insufficiency, but no further surgery was done. In three patients with mitral valve repair, contrast-echocardiography showed severe insufficiency, which had not been detected during cardiac arrest. In these patients changes in the level of the subvalvular apparatus caused systolic dislocation of the leaflets and massive reflux. Because of these findings definive valve replacement was performed in the same operation. Intraoperative TEE is a simple, safe and reliable method für assessment of AV-valve repair, thereby motivating the surgeon towards valve preservation and improving the outcome of valve surgery.