Abstract: The tegumental structure of adult Clonorchis sinensis was studied with scanning electron microscopy. At low magnifications, the body surface was seen to be marked with numerous irregular ridges encircling the body. At high magnifications, the surface of the tegument was observed to consist of knoblike protuberances. The oral sucker was larger than the ventral one and formed an angle of 110° with the ventral surface. The excretory pore was situated at the most posterior point of the body.Presumed sensory papillae were seen on the lips of the oral and ventral suckers, on the body surface surrounding the suckers and on the body surface around the excretory pore. Papillae found on the lip of the ventral sucker and on the body surface encircling both the oral and ventral suckers were densely distributed and rather randomly scattered over the remainder of the body. The papillae were divided into five types: 1. Ciliated rosette-form papillae on the body surface around the oral sucker; 2. Ciliated spiral papillae on the body surface surrounding the excretory pore; 3. Round swellings of nonciliated papillae on the lips of the oral and ventral suckers; 4. Nonciliated spiral papillae on the body surface around the oral sucker; 5. Nonciliated buttonlike papillae on the body surface encircling the oral sucker.