A device for separating regions of a space which includes at least two ceiling rail parts for pressing against the ceiling of the space, the profile sections of the ceiling rail parts allowing adjacent parts to be inserted into and pulled apart from one another for adjusting the length of the ceiling rail. In like manner, the device includes a floor rail and at least one support rail extending between the ceiling rail and the support rail, each of which rails also has at least two rail parts which can be inserted into and pulled apart from one another for adjusting the length of the rails. In one embodiment, a ceiling rail, floor rail and two support rails form a peripheral rectangular frame with the rails in contact with the adjoining ceiling, floor and/or walls.