Method and device for checking the liquid take up of a test layer of an analysis element. The test layer is absorbent and takes up a liquid when an analysis is carried out. The test layer is illuminated with primary light to generate a light signal characteristic of the liquid take up. Secondary light emerging here from the analysis element is detected. The test layer is in contact with an optically transparent foil segment. Reliably checking liquid take up is achieved by detecting secondary light emerging from the circumferential surface of the foil.