Abstract: The subject of the invention is an apparatus for homogenizing liquid and viscous substances, which consists of a high-pressure pump with a crank drive and at least one piston guided in a cylinder block and driven by means of connecting and side rods, and a homogenizing unit, which is arranged on the cylinder block of the high-pressure pump by means of an intermediary chamber that may be opened. The homogenizing unit has a two-part homogenizing head, which consists of a sleeve with a smooth-walled, conical let-through borehole opening out on the outlet side and a plunger held in this borehole by axial compression and guided by guide projections into the corresponding recesses arranged in the sleeve, which plunger has a solid section of essentially truncated-cone-shaped surface area, on which axial and successive ring-shaped steps are constructed, each step having its external periphery adjacent to the borehole.