Duvernoy's gland, an oral gland located in temporal region, is only found in Colubrid snakes. This is the first report describing morphological and histological structure of Duvernoy's gland in Natrix tessellata (Laurenti, 1768). It is surrounded by a connective tissue layer which penetrates into the gland by forming many septa, dividing the glandular body into lobules and including the acini and the inner ducts. Duvernoy's gland is formed by seromucous acini composed of seromucous cells, and mucous acini composed of mucous cells and they are recognized by their histochemical characteristics. The gland is mainly organized in seromucous acini, mucous cells are restricted to the gland center region and to the inner secretion duct lining epithelium.