It has been shown that alpha-Gal is a relevant xenoantigen present on bioprostheses and elicits a specific IgM immune response. The aim of this work was to investigate whether that immune response proceeds after valve implantation. Plasma samples were collected from patients who underwent biovalve implantation or mechanical valve replacement, prior to, at ten days and at three months after cardiac surgery. ELISA was performed to quantify Gal specific antibodies. Three bioprosthetic tissue samples were obtained from patients who had to undergo reoperation within one week or one year after the initial operation. Presence of Gal epitopes and cell nuclei was determined. Alpha-Gal specific IgG was significantly increased three months after implantation of bioprostheses. In explanted bioprostheses one year after implantation, no Gal epitopes could be detected. These results indicate that the implantation of bioprostheses elicits a specific immune response against Gal bearing cells. The complete absence of Gal positive structures 12 months after implantation indicates a specific degradation of Gal bearing cells through previous exposure to the human blood circuit.