A tape cassette for a medical handheld device is disclosed as comprising a carrier tape, which carries test fields for assaying a sample of a human or animal bodily fluid and/or lancets as functional elements, a supply chamber, in which a supply section of the carrier tape comprising unused functional elements is positioned, a winding unit, in order to wind up the carrier tape and draw it through a tape exit opening of the chamber, so that the functional elements may be brought sequentially into a usage position. The carrier tape in the tape exit opening is oriented transversely to the supply section positioned in the supply chamber.