The invention relates to a pressure booster arrangement for high-pressure injection systems or high-pressure injection system parts of internal combustion engines. A differential piston which operates with a large cross section in a medium-pressure reservoir and with partial cross sections is operative in terms of positive displacement in associated control and work pressure chambers that are separate from the medium-pressure reservoir and that are disposed in a guide body. The guide body guides the differential piston in its strokes and in turn axially adjoins a valve body. The valve body receives control and check valves for controlling communicating lines of the guide body and of the valve body for controllably connecting the control and work chambers to the medium-pressure reservoir or to a relatively pressureless fluid reservoir. It is essential to the invention that the valve body and the guide body separate from it, which at least on its end remote from the valve body is acted upon by the pressure in the medium-pressure reservoir, adjoin one another axially with end faces facing toward one another. Between these end faces, a spacer chamber or hollow chamber communicating with the relatively pressureless reservoir is embodied.