The study of oral mucosa functional state is critical task when conducting both science research and clinical diagnostic. The development of a complex of morphological methods, allowing a comprehensive assessment of rat oral mucosa functional state in normal condition and experimental pathology was the aim of this work. We proposed a complex of morphological methods, including both classical histological methods (hematoxylin and eosin stain, Masson's aniline blue stain, toluidine blue stain) and modern immunohistochemistry methods (immunohistochemical reaction to histone H3 and to smooth-muscle α-actin). The use of this complex allows us to qualitatively and quantitatively assess the oral mucosa using such parameters as the presence (or absence) of inflammation, connective tissue density, presence (or absence) of mast cells, mast cell degranulation index, cell proliferative activity, state of the blood vessels, and draw a general conclusion about the morphofunctional status of mucosa.