We present a case of left ventricular pseudoaneurysm diagnosed by chance 6 years after a second surgical intervention on the mitral valve (replacement with a St. Jude prosthesis). A combination of cross sectional and color-Doppler studies led to the correct diagnosis. A transesophageal echocardiographic investigation did not provide further information, while the diagnosis was confirmed by computed tomography with contrast agent. A retrospective analysis of previous examinations revealed that the pseudoaneurysm developed shortly after the mitral valve replacement, remaining stable over the years. The patient was clinically asymptomatic, the size of the pseudoaneurysm did not increase during a 2 years followup, and we decided to follow a conservative treatment.