A refrigeration appliance having an interior refrigeration cabin enclosed by a heat-insulating housing and at least one food carrier shelf for storing food items in a refrigerated manner, the shelf having a front edge extending between lateral walls of the refrigeration cabin and being equipped with a height adjustment mechanism associated therewith so as to effect changing of the level of the shelf in case a food container placed thereon needs an increased space, wherein - a main shaft is provided in association with the shelf along each lateral wall, with first and second worm gear portions (7, 8) extending on both ends of the main shaft such that rotation of the first worm gear portion simultaneously effects rotation of the second worm gear portion together with the first worm gear portion in a first direction, characterized in that - the first and second worm gear portions (7, 8) have teeth inclined in opposite directions. - a first and second reducer mechanism (9, 10) is mechanically coupled respectively with the first and second worm gear portions (7, 8) such that displacing thereof effects changing of the level of the shelf, - the first and second reducer mechanisms (9, 10) have teeth inside inner cavities thereof being inclined in opposite directions, - the first and second reducer mechanism (9, 10) are respectively meshed with the first and second worm gear portions (7, 8), - the first and second reducer mechanisms (9, 10) meshed with the first and second worm gear portions (7, 8) are imparted linear movement in opposite directions by the rotation of the first worm gear portion, - the first and second reducer mechanisms (9, 10) are each connected to a guided roller, the latter being movable in a inclined guiding channel on the lateral walls of the refrigeration cabin, - the first worm gear portion communicates with a slider via a driving strap engaging with radial teeth of the first worm gear portion, - the radial teeth of the first worm gear portion are in continuous engagement with the driving strap. - a main shaft is provided in association with the shelf along each lateral wall, with first and second worm gear portions (7, 8) extending on both ends of the main shaft such that rotation of the first worm gear portion simultaneously effects rotation of the second worm gear portion together with the first worm gear portion in a first direction, - the first and second worm gear portions (7, 8) have teeth inclined in opposite directions. - a first and second reducer mechanism (9, 10) is mechanically coupled respectively with the first and second worm gear portions (7, 8) such that displacing thereof effects changing of the level of the shelf, - the first and second reducer mechanisms (9, 10) have teeth inside inner cavities thereof being inclined in opposite directions, - the first and second reducer mechanism (9, 10) are respectively meshed with the first and second worm gear portions (7, 8), - the first and second reducer mechanisms (9, 10) meshed with the first and second worm gear portions (7, 8) are imparted linear movement in opposite directions by the rotation of the first worm gear portion, - the first and second reducer mechanisms (9, 10) are each connected to a guided roller, the latter being movable in a inclined guiding channel on the lateral walls of the refrigeration cabin, - the first worm gear portion communicates with a slider via a driving strap engaging with radial teeth of the first worm gear portion, - the radial teeth of the first worm gear portion are in continuous engagement with the driving strap.