An apparatus for the evaluation of a flat test carrier for the analytical determination of components of a body fluid includes a measurement unit and a positioning means adapted to position and firmly hold a test carrier in a measurement position in such a manner that its test field is present in a definite position with regard to the measurement unit; the apparatus is especially useful for the evaluation of test carriers with a covering layer fixed in the manner of a flap on one edge of the test carrier; the apparatus comprises an aperture element with a contact surface adapted to press on the covering layer, at least one of the aperture element and the positioning means being mounted and operable in such a manner that the contact surface in the last phase of approaching the covering layer is adapted to make, relative to the test carrier, a tilting movement about a tilting axis which lies in close proximity to the fixing edge of the covering layer.
