A grass cutting assembly which is provided with a grass cutting unit with a rotor provided with a number of cutters for cooperation with a fixed blade, as well as a receptacle bin for grass cuttings. The receptacle bin has a fixed portion connected with the grass cutting unit and a partly cylindrically arcuate bottom portion which is pivotally connected to the fixed portion and is pivotal between a closed and an open emptying position. The pivotal axis of the bottom portion is horizontal and parallel with the axis of rotation of the rotor.