The invention is a delivery compensation unit for plaster sprayers comprising a frame (3) that supports a tank (4) containing the plaster (I) to be sprayed; a pumping unit (6) for conveying the plaster (I) through suction from the tank (4) to a suction chamber (6a) and through compression from the suction chamber (6a) to a compression chamber (6b); an outlet pipe (7) connecting the compression chamber (6b) to a spray gun; ball valve means (13a, 13b) for placing the tank (4) in communication with the suction chamber (6a) and the suction chamber (6a) with the compression chamber (6b). A cylindrical container (19) closed at one end by a bottom (20) defines a compensation chamber (22) having an inlet mouth (21) connected to the chamber provided with a sliding plunger (23) and elastic mechanical means (24) interposed between the plunger (22) and the bottom (20).