An apparatus for movable fastening of a laboratory unit to a horizontally extending, elongated ceiling beam which is mounted in the region of a room ceiling and has at least one first groove which extends in the lengthwise direction of the ceiling beam. The apparatus includes: (i) a sliding element engageable with the first groove of the ceiling beam such that the apparatus is movable in lengthwise direction of the first groove, wherein a height of the sliding element is substantially equal to a height of an access opening to the groove, (ii) a retaining element for detachably fastening the laboratory unit, and (iii) at least one locking element which can be connected to the ceiling beam such that the apparatus is prevented from moving in the lengthwise direction of the first groove.