For determining autofluorescence of a clinically normal skin issue (7) of a patient, the tissue (7) is irradiated with electromagnetic radiation. An amount of fluorescent radiation emitted by the tissue (7) in response to the irradiation is measured and, in response thereto, a signal is generated which represents a determined autofluorescence in agreement with the measured amount of electromagnetic radiation. Because the tissue (7) is skin tissue (7) in vivo and irradiation is performed noninvasively, a method which is very simple to apply for determining autofluorescence is obtained. An apparatus especially adapted for use in this method is also described.