A 22-year-old male presented with infective endocarditis and aortic regurgitation with congenital bicuspid aortic valve. Echocardiography revealed vegetation on the aortic valve and a pseudoaneurysm in the region of the mitral-aortic intervalvular fibrosa (MAIVF) with severe aortic and mitral regurgitation. His clinical condition, acute heart failure due to severe aortic and mitral regurgitation, became worse. Since the MAIVF complication indicates advanced disruption of tissue at the MAIVF, urgent cardiac surgery was indicated because of the evidence of pseudoaneurysm. He received successful aortic valve replacement and restoration of normal mitral-aortic continuity. Pseudoaneurysm of the MAIVF is a relatively rare complication of infective endocarditis, but should be considered in patients who are suspected to have vegetation because echocardiography can easily establish the correct diagnosis.