Abstract: The antitumor activity of Sb-derivatives of complexones has not yet been reported in the literature.In this work we found that Sb-26 (Sb Na ethylenediamine tetraacetate 15—20 mg/kg), Sb-57(Sb Na propylenediamine tetraacetate 30—50 mg/kg),Sb-66(Sb β-hydroxyethyl imino- diacetic acid 25—30 mg/kg)and Sb-71(Sb ammonia triacetic acid 20—40 mg/kg)could significantly inhibit the growth of Ehrlich ascites carcinoma of mice and prolonged the survival time for 4—22 days(36—147%,P<0.05)in comparison with the control group.These com- pounds at the above mentioned dosages inhibited also the growth of Guerin’s carcinoma.The degree of inhibition was about 58—70%(P<0.05).The survival time of mice bearing spindle cell sarcoma(in ascitic form)was also prolonged for 5—16 days(50—160%,P<0.05)by treatment with the latter three drugs,among which Sb-71 was most active. Experiments were carried out on mice bearing sarcoma 180 or sarcoma AK treated with Sb-26,Sb-57,Sb-71 or Sb-66 and on mice bearing Ehrlich carcinoma or lymphatic leucemia (solid form)treated with the former three drugs.It was found that only Sb-71 possessed certain inhibitory action on sarcoma 180. In the present study,Sb-8,Sb-11,Sb-42,Sb-15,Sb-64 and Sb-85 were all lacking in inhibitory effect on Ehrlich ascites carcinoma of mice. In mice,the acute LD₅₀levels after intraperitoneal injections of Sb-57 and Sb-71 were found to be 131 and 62 mg/kg respectively;the subacute LD₅₀(10 injections)were equal to 75 and 58 mg/kg respectively.