Aortic transplantation has progressively gained interest over the last few years and it is becoming a first choice indication in the substitution of infected prostheses. The most frequent complication in long-term vascular outcome (wall thickening, aneurysmatic dilation, stenosis), may occur through an immunological mechanism. In this study we investigated nine recipients, aged 48 to 65 years, of aorta segment replacement for anti-HLA antibody production (specificity and Ig class), CD3-CD4-CD8 T cell subpopulation dynamics and aorta wall thickness. Mismatch-specific IgG antibodies to HLA class I and HLA class II antigens were detected 1, 3 and 6 months after transplantation and persisted at a high concentration for at least 1 year. Furthermore, the absolute number of CD3, CD4 and CD8 positive lymphocytes increased progressively after aorta allograft. Tomography scanning showed a progressive thickness of the aorta wall. We can speculate that these anti-HLA antibodies in the recipients have the potential to harm the implant; therefore, aorta allograft should involve the induction of immunological tolerance by appropriate immunosuppressants.