PileMC is a tool for the simulation of pile-up events at HepMC level. Technically, PileMC reads two HepMC files, one of which contains signal events and the other one contains minimum-bias events. The program generates a HepMC file containing signal events superimposed with min-bias events, yielding an event-generator-level approximation to the presence of pile-up in high-luminosity collisions.