An assembly for automatically opening and closing a sliding door of the type including a fixed panel and a moving panel which slides on a track relative to the fixed panel. The assembly comprises a housing defining an internal space; a support frame defining a space which receives and retains a drive assembly including a motor having a drive shaft; a drive wheel operably linked to the motor via said drive shaft. The assembly also includes an idler pulley; at least one drive belt associated with said drive wheel and the idler pulley; wherein, when the drive wheel is energised by the motor, motion is imparted to the drive belt thereby causing the movable panel of the sliding door to move between a first state when the door is closed and a second state when the door is open.