The invention relates to the preparation and use of &alpha；,&bgr；-unsaturated aldehyde of hyaluronan having a double bond in the positions 4 and 5 and an aldehydic group in the position 6 of the glucosamine part of the polysaccharide. The method of preparation is based on dehydration of hyaluronan having an aldehydic group in the position 6 of the glucosamine part of the polysaccharide. Two methods have been described, which are dehydration in a solution or heating in solid state in absence of solvents, bases or other additives. This derivative allows stabilization of conjugates of hyaluronan with amino compounds by means of a multiple bond from the aldehyde side, and therefore, it is possible to effectively immobilize practically any compound containing an amino group to such modified hyaluronan in physiological conditions. In case of using a diamine or compounds or polymers containing three or more amino groups, it is possible to prepare crosslinked hyaluronan derivatives. The described solution brings along a significant advantage not only in the field of carriers of biologically active substances, but also in tissue engineering where crosslinking with biologically acceptable amino compounds in physiological conditions is very much demanded.L'invention concerne la préparation et l'utilisation d'aldéhyde α, β insaturé d'hyaluronane ayant une double liaison dans les positions 4 et 5 et un groupe aldéhyde dans la position 6 de la partie glucosamine du polysaccharide. Le procédé de préparation est basé sur la déshydratation d'hyaluronane ayant un groupe aldéhyde en position 6 de la partie glucosamine du polysaccharide. Deux procédés ont été décrits, qui sont la déshydratation en solution ou le chauffage à l'état solide en l'absence de solvants, de bases ou d'autres additifs. Ce dérivé permet la stabilisation de conjugués d'hyaluronane avec des composés amino au moyen d'une liaison multiple à partir du côté aldéhyde, et en conséquence, il est possible d'immobiliser de
