A method for determining an autofluorescence value of skin tissue of a subject, comprising the steps of: - irradiating material of said skin tissue with electromagnetic excitation radiation of a wavelength or wavelength range within the excitation range of wavelengths of 300-420 nm; - measuring an amount of electromagnetic, fluorescent radiation emitted by said material in response to said irradiation over a range of wavelengths of 420-600 nm; and - generating, based upon said measured amount of fluorescent radiation, a measured autofluorescence value for the concerning subject; - measuring a first measured reflectance at a first wavelength or wavelength range and a second measured reflectance at a second wavelength or wavelength range different from said first wavelength or wavelength range, wherein said first and second wavelengths or wavelength ranges are both within the excitation range of wavelengths with which the skin tissue is irradiated for excitation, or both within the range of wavelengths in which the emitted fluorescent radiation is measured, or both in a range of wavelengths higher than 620 nm, or wherein said first wavelength or wavelength range is in a range of wavelengths of 450-525 nm and said second wavelength or wavelength range is in a range of wavelengths higher than 620 nm; and - generating a corrected autofluorescence value by correcting the measured autofluorescence in accordance with a relationship between said first and second measured reflectances in such manner that the dependency of the corrected autofluorescence value upon different UV-skin tissue reflectances, that different respective subjects may have, is minimized or at least diminished - irradiating material of said skin tissue with electromagnetic excitation radiation of a wavelength or wavelength range within the excitation range of wavelengths of 300-420 nm; - measuring an amount of electromagnetic, fluorescent radiation emitted by said material in response to said irradiation over a range of wavelengths of 420-600 nm; and - generating, based upon said measured amount of fluorescent radiation, a measured autofluorescence value for the concerning subject; - measuring a first measured reflectance at a first wavelength or wavelength range and a second measured reflectance at a second wavelength or wavelength range different from said first wavelength or wavelength range, wherein said first and second wavelengths or wavelength ranges are both within the excitation range of wavelengths with which the skin tissue is irradiated for excitation, or both within the range of wavelengths in which the emitted fluorescent radiation is measured, or both in a range of wavelengths higher than 620 nm, or wherein said first wavelength or wavelength range is in a range of wavelengths of 450-525 nm and said second wavelength or wavelength range is in a range of wavelengths higher than 620 nm; and - generating a corrected autofluorescence value by correcting the measured autofluorescence in accordance with a relationship between said first and second measured reflectances in such manner that the dependency of the corrected autofluorescence value upon different UV-skin tissue reflectances, that different respective subjects may have, is minimized or at least diminished