Abstract: The antitumour activity and toxicity of Sb-71 (Sb ammonia triacetic acid) were reported in our previous papers. In the present study, we have investigated the antidotal action of several sulphhydryl compounds against Sb-71 and their influence upon the inhibiting action of Sb-71 on Ehrlich ascites tumour in mice. The results were as follows: 1.Subcutaneous injection of sodium dimercaptosuccinate, BAL-glucoside, BAL, and cysteine at the dose levels of 500, 1167, 30, and 1000 mg/kg respectively exhibited a significant protective action upon mice intoxicated by Sb-71, decreasing the mortality rate of mice. 2.The administration of sodium dimercaptosuccinate (1500 mg/kg), BAL-glucoside (2000 mg/kg), BAL (40 mg/kg), and cysteine (1000 mg/kg) increased the LD₅₀ of Sb-71 from 40 mg/kg to 232, 76, 68, and 87 mg/kg respectively. 3.Sodium dimercaptosuccinate, BAL-glucoside, and BAL could also antagonize the carcinostatic action of Sb-71, but its therapeutic effect could recur when the dose level was increased with the exception of BAL. Cysteine at the dosage of 500 mg/kg also showed the antidotal action, but did not diminish the therapeutic effect of Sb-71. The possible mechanisms of the antidotal action of these sulphhydryl compounds in the present work were discussed.