Blood withdrawal system for withdrawing blood for diagnostic purposes, comprising a housing with an outlet opening for the tip of a lancet, a lancet guide and a lancet drive. The lancet drive comprises a plural lever coupling mechanism, forming a connection between the drive element and the lancet during the puncturing movement and comprising two levers connected to each other via a first swivel joint, wherein one of the levers is coupled to the lancet with its end facing towards the lancet by means of a second swivel joint, and the second lever comprises a third swivel joint at the end facing away from the lancet. During the cocking movement, the freedom of movement of the lancet is limited in such a manner that the lancet tip does not protrude from the outlet opening.