The aim of this study was to investigate the influence of stenting on amino-oleic acid (AOA)-treated, glutaraldehyde-fixed porcine aortic valve bioprostheses. Twelve young sheep underwent implantation of porcine aortic valves in the pulmonary artery: six porcine aortic stentless valves (Freestyle®) and six porcine aortic stented valves (Mosaic®). In each series, three valves were explanted after three months, and three after six months. Valves were analyzed by gross inspection, radiography, histology, transmission electron microscopy and quantitative determination of the calcium content. The cusps of stentless valves contained significantly less calcium than those of stented valves at six months after implantation. However, the aortic wall of stentless valves contained significantly more calcium than that from stented valves. These data suggest that stenting influences cuspal calcification of AOA-treated, glutaraldehyde-fixed porcine aortic valves.