he development of nervous system of Clonorchis sinensiswas studied by the thiocholine method for local-ization of cholinesterase.The nervous system of 5-day-old juveniles is revealed as the prodium of the adults. It is composed oftwo nerve ganglia

and the nerve trunks stemming from the ganglia. The anterior nerve trunks are not con-spicuous.The best devloped is posteroventral nerve trunk. The posterodorsal nerve trunks join near the end.The thinnest pair is lateral nerve trunk.There are four or five transverse commissures between the gangliaand the acetabulum

more than ten from the acetabulum to the end. The acetabulum is innervated by nervebranches from the posteroventral nerve trunks.In 10-day-old juveniles

a perfect nervous system is seen and its anterior nerves exstending to the oralsucker

and more transverse commissures forming a nerve network with the nerve trunks. During 20 sticces-sive days

only slight changes have been noted in the detailed structure of the system

namely

the cerebralganglia become more visible and transverse commissures increased.The nervous system of 30-day-old adults fits the pattern described as the juveniles;The results stig-gested that the pattern of nervous system be constant from Juveniles to adults of Clonorchis sinensis.