A sample-taking unit having a sampling unit and a hold-down device which is movable relative thereto in a parallel manner, said sample-taking unit including a self-holding mechanism which, as a result of a self-locking effect, automatically fixes the hold-down device in a lowered fixing position against an upward movement until the self-locking effect is removed again as a result of the self-holding mechanism being acted upon with a detaching force, preferably as a result of contact between the sampling unit and a clamping element of the self-holding mechanism.