The invention concerns a planetary gear box, which has a sun gear, a plurality of planet gears, a ring gear and a plurality of plain bearing pins. Here, a plain bearing pin is arranged in each planet gear, wherein the plain bearing pin and the planet gear form a lubricated plain bearing, and the plain bearing pin forms a crowning at its contact face, wherein the outer diameter of the contact face decreases from a maximum outer diameter towards at least one axial end of the contact face. The crowning of the contact face is configured such that the contact face is concavely shaped adjacent to at least one axial end of the contact face or to a cylindrical region adjoining the axial end.