Abstract: The invention relates to a plain bearing shell (2), having a substantially semicylindrical geometry, for use in a piston (50) of a radial piston engine for the purposes of mounting a roller or shaft, having an axial direction (4), a radial direction (6) and a circumferential direction (8) of the plain bearing shell, having two face sides (10, 12) which face away from one another in the axial direction (4), having a radially outer side (14) and a radially inner side (16) which faces toward the roller or shaft and which receives said roller or shaft such that it can slide in the circumferential direction (8); it is proposed according to the invention that, on at least one face side (10, 12), there is provided a projection (18) which protrudes in the axial direction (4) of the plain bearing shell and which serves to form a means for preventing rotation in the circumferential direction (8).