Abstract: The induction of routine non-speciflc killer cells in vitro by Thymosin, Pingyangmycin(PYM)and Adriamycin (ADM) has been examined and the eff- ects of combination of Thymosin wiih ADM or with PYM were also observed. BALB/c mouse spleen ceils cultuged with Thymosin showed significant cytotoxicity against YAC-1 tumourr cells in aSH PdR releage assay. Treatment of murne splenocyteg with PYM or ADM ahowedenhancement of killer activity respectively. In an additive effecie were detected in the spleen cells cultured with Thymosin and PYM, or with Thymosin and ADM. The results indieate that Thymosin can regttlate nonspeeifie killers activity and might have better antitttmor effect when it eombined with PYM or with ADM.