The objective of the present study was to evaluate the potential of autofluorescent stomatoscopy with the use of the photodiode-based fluorescence detection system for diagnostics of lichen planus as the pre-cancerous state of the mucous membrane of the oral cavity (OCM). The visual examination of the oral cavity mucosa was carried out using the photodiode-based apparatus for fluorescence detection (registration certificate No FSR 2011/1066669, Moscow). This article was designed to report the results of the autofluorescent stomatoscopy of the patients presenting with such pre-cancerous condition of oral mucosa as lichen planus. It is shown that the examination of the oral cavity mucosa with the help of the photodiode apparatus reveals lichen planus foci visualized in the form of the “black spots” against the background of intense green fluorescence emitted by the normal mucous membrane. This method makes it possible not only to detect the pathologically changed sites but also to determine their boundaries. It is concluded that autofluorescent stomatoscopy with the use of the photodiode-based fluorescence detection system can be regarded as the new promising technique for oncoscreening in stomatology.