The vas deferens wall of Pergamasus viator Halas. is built by epithelial cells, striated muscle cells and basement membrane. The epithelial cells, 35 to 40 micometer in diameter, contain in their cytoplasm the endoplasmic reticulum surrounding the nucleus in a characteristic arrangement, numerous Golgi complexes, mitochondria, microtubules, and two types of vacuoles. The luminal part of plasmalemma forms scarce microvilli. The mononuclear muscle cells with the maximal thickness of 5 micormeter, as measured at the level of nucleus, possess numerous processes and in their cytoplasm there are mitochondria, microtubules, cisternae of sarcoplasmic reticulum, lysosome-like vacuoles, and myofibrils composed of thick and thin myofilaments. Each of thick filaments (200 Angstrom) is surrounded by 10 to 12 thin filaments (50 Angstrom). The Z lines show irregular contours. The basement membrane enclosing from the outside the whole vas deferens, consists of several layers, each zoo A thick. The secretory role of epithelial cells in the vas deferens is discussed.