Three copolymers were made from the suspension polymerization of methyl acrylate, divinyl benzene and triallyl isocyanurate; acrylamide and N,N'-methylene-bis-acrylamide; and styrene and divinyl benzene. These copolymers were then converted into derivatives of hydrazides through several steps. They were used as polymeric sorbents. They sorbed in situ a little bit less than 40 mg. of urea per gram of sorbent at 37 degrees C, pH = 7.0-7.4 and the percentage of urea in the buffer solution being 130 mg%. The sorption of urea was related to the specific surface area of the sorbent, temperature of sorption and time of sorption, concentration of urea, pH value of solution etc. In order to find out whether the above-prepared derivatives of hydrazide can be used clinically as polymeric sorbents in artificial kidney system, the junior author carried out experiments with patient's dialysate as imitated to hemodialysis. From the results, it indicates the sorbents might be used in artificial kidney system because they sorbed the urea from hemodialysate as much as that of the pure urea in a buffer solution.