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...