The invention concerns an analytical instrument for assaying body fluids, the instrument having the following features: a) a housing provided with a receiving element for engaging a body part, b) an abutment for the body part which can be moved between a release position and an operating position relative to the receiving element, c) a lancing unit having a lancing element that can pierce the bodypart resting against the abutment in a linear lancing stroke, d) a test tape unit having a test tape for receiving body fluid issuing from the body part, and e) a detection unit for examining the bodyfluid applied to a section of the test tape.