The 76-year-old woman underwent double bioprosthetic valve replacement for aortic and mitral valve regurgitation without any postoperative complication. About 33 months later, the patient complained of sudden dyspnea and was diagnosed with mechanical hemolytic anemia, severe aortic regurgitant jet collision with stent post (SP) at mitral position and acute heart failure. The cause of mechanical hemolysis was suspected to be a collision of the regurgitant jet due to structural valve deterioration (SVD) with the SP because of the absence of any paravalvular leak (PVL). The externally-mounted bioprosthetic aortic valve was replaced and the inadequate projection of the SP in left ventricular outflow tract was recognized simultaneously. The patient fully recovered from heart failure and hemolytic anemia after surgery. Early SVD of externally-mounted bioprosthetic valves has often been reported, and the eccentric regurgitant jet due to SVD may collide with any sub-valvular structures. We report a rare case of hemolytic anemia due to SVD.