Diethyl-dithiocarbamate (DDC) is a compound with wide spectrum of pharmacologic activities. It has been shown to enhance the tumor cytotoxic effect of Pingyangmycin (PYM). In this paper, the effect of DDC on the distribution of 99mTc-labeled PYM in mice bearing subcutaneous transplant of Ehrlich carcinoma is reported. The results indicate that DDC did not affect the absolute concentration of PYM in the tumor but it accelerated its excretion in the urine and decreased the concentration of PYM in the non-tumorous tissues. Therefore, DDC could help alleviate the damaging effect of PYM on normal tissues without affecting its tumor cytotoxic activity.