A camshaft adjuster for an internal combustion engine having hydraulic medium guides. The adjuster can include a setting unit that can be controlled by a control unit using these guides in the adjuster, wherein the setting unit is for adjusting an angle of a camshaft. This setting unit has an inner body coupled to the camshaft so as to rotate with it, and an outer body that is mounted to rotate relative to the camshaft via a drive connection which runs from a crankshaft to the camshaft. The camshaft has at least one insert part permanently inserted camshaft wherein these two components together form at least one hydraulic medium guide at least in partial regions over its axial length. This design is to create a camshaft adjuster which is in interaction with a camshaft having an insert part so that there is a simple and reliable supply of hydraulic medium to the camshaft adjuster and in particular to its control device.