A connection device for a catheter, in particular a peripheral venous catheter, comprising: a) a main body having a main body infusion channel and a through-flow element having a sterilizing effect and forming at least one part of the main body infusion channel, wherein the through-flow element has an inlet opening, a liquid-tight circumferential wall, and an end wall which is arranged opposite the inlet opening and has at least one outlet opening, and b) an attachment body having an attachment body infusion channel and being detachably fixed on the main body, characterized in that the through-flow element enters a sealing press fit with the attachment body infusion channel through an attachment body fixed on the main body.
