The nervous system of adult Diplostomum pseudospathaceum Niewiadomska, 1984 was studied using Koelle's (1951) method for revealing cholinesterase activity. The nervous system in the fore body grows but its pattern remains the same as in the metacercaria: three pairs of stems connected by numerous commissures and differentiated innervation of various organs in this part of the body. In the elongated hind body the nervous system develops according to another pattern: two pairs of stems connected by a number of commissures form a loose net surrounding the whole segment. The net is more dense at the body end around the genital opening and copulatory organs. A brief discussion of the development of the nervous system of D. pseudospathaceum from cercaria to adult stage is given.