NEW MATERIAL: The human thymopoietin which is free of non-human thymopoietin native matter and has the amino acid residue sequence expressed by formula, etc.

USE: A cellular immunopotentiator and chronic infection therapeutic agent.

PROCESS: For example, the human thymus gland is homogeneized in 100 mM ammonium hydrogencarbonate and the supernatant is collected after extraction and centrifugal sepn., following which the supernatant is processed with a membrane for sepn. and is then thickened and is fractionated by chromatography. Next, the immunoreactive fragments are collected, thickened and desalted and are then processed with an anion exchange column and thereafter, the fragments are eluted at a linear solvent gradient by a tris acetate buffer soln. The immunoreactive fragments are combined and are refined by reversed phase column chromatography and thereafter, the immunoreactive fragments are freeze dried, by which the human thymopoietin is obtd.