The aim of this study was to compare the fluorescence of different areas of the buccal mucosa of dogs. Native fluorescence occurs in many animal and plant tissues following excitation by ultraviolet (UV) light. The fluorescence spectrum characteristic of a given tissue may vary with changes in tissue composition and organization. Hence, this optical phenomenon provides a reliable and minimally invasive diagnostic tool for examining tissues in normal and pathological conditions. The oral cavity contains a variety of structures, including the lips, tongue, palate, and gingiva that differ in their location and function. These structures can be easily traumatized or display different degrees of keratinization. The study sample was 20 healthy, adult, mongrel dogs of both sexes. The dogs were anesthetized and manipulated in compliance with institutional guidelines. The fluorescence spectra were obtained using a plug-in spectrometer and optical fibers, with a final resolution better than 2 nm. The fluorescence of seven different areas (floor of the mouth, palate, gingiva, dorsal and ventral surface of tongue, buccal mucosa, and teeth) was examined. A UVHg lamp (emission wavelength, 350-410 nm) was used for excitation. One hundred and forty spectra were collected from various regions of the oral cavity, and all of them showed similar profiles, with maximum fluorescence of 500-520 nm. The similarity of the spectra for the different sites allowed us to establish a standard fluorescence spectrum of the buccal cavity.2422-8