A piston pump, in particular a high-pressure fuel pump for an internal combustion engine, includes a pump housing, a pump piston, and a delivery chamber that is delimited at least by the pump housing and the pump piston. The piston pump further includes a seal configured to seal the delivery chamber and a separate guide element configured to guide the pump piston. The seal and the guide element are arranged between the pump piston and the pump housing. The seal is formed as a plastic ring with a substantially sleeve-shaped base portion.