The cestode tegument acts not only as a protective coat but also serves as a metabolically active layer for nutrient absorption from ambient medium of the host. The author aims to study the tegument ultrastructure throughout the body length of a cyclophyllidean davaineid adult cestode, Raillietina sp. infecting fowl in West Bengal, India and try to compare the outcome with other such groups. The basic tegumental architecture of this cestode is more or less similar in all the zones studied. However, variations noticed in microtriches, distal cytoplasm, internuncial processes, tegumental cells etc. in pre-gravid and gravid zones are to compensate various complex physiology of the cestode to perpetuate better endoparasitic life.