Twelve rabbit jugular veins were studied in order to determine if viscoelastic substances (1% Sodium Hyaluronate and Collagen IV) allowed a better endothelial preservation than normal saline solution. Veins were stored at 4 degrees C for either one or three hours. Endothelial integrity was analysed by scanning electron microscopy. The best endothelial preservation was obtained with normal saline solution. We conclude that endothelial preservation is not enhanced by viscoelastic substances.