The aim of the study was to establish the ultrastructural organization features of the gallbladder mucous membrane of an Anglo-Nubian goat. The material for the study was the gallbladder wall’s fragments of an adult Anglo-Nubian goat. Further processing of the obtained samples was carried out according to generally accepted methods. Ultrathin sections were photographed in a Jem-1011 electron microscope at magnifications of 2500-3000. It was found that the gallbladder mucous membrane of an Anglo-Nubian goat is formed by the epithelial layer and its own lamina. The epithelial layer is represented by a single-layer prismatic epithelium, which cells lie on a dense basement membrane. Their nuclei are light, with clear contours. The cytoplasm contains many small mitochondria, vesicles, a small Golgi complex, short cisterns of the granular endoplasmic reticulum, ribosomes, polyribosomes, and rare lysosomes. The apical surface of epithelial cells forms microvilli, and the cytoplasm of the apical pole of cells contains many electron-dense secretory granules. The secret of the latter is excreted into the lumen of the gallbladder, forming a thin layer of glycocalyx on the surface of the epithelium. The lateral surfaces of the cells in their apical part are interconnected by tight contacts. The lamina propria is formed by loose connective tissue containing many blood vessels and nerve fibers.