A device for measuring the fluorescence of a medium having a radiation source, an emission-receiving element and an optical imaging element arranged on the sensor side of the optical imaging element, and a scattering-receiving element arranged on the sensor side of the optical imaging element and in which the radiation source, the imaging element and the emission-receiving element are aligned and configured relative to one another so that the medium present on the medium side of the imaging element can be illuminated by radiation from the radiation source, and the emission intensity of the medium radiation emitted by the medium based on fluorescence can be detected with the emission-receiving element. To provide a device for measuring the fluorescence of a medium which has an increased reliability in measuring the fluorescence, temperature compensation is performed relative to the temperature of the medium and/or at least one of the receiving elements.