It has been shown by several investigators that tumor cell emboli are present in the blood stream of patients with carcinoma. Cancer cells were demonstrated in the venous blood draining organs involved by cancer by McGrew et al.1 and by Fisher and Turnbull.2 Engel3 and Moore et al.4 have also demonstrated the presence of tumor cell emboli in the peripheral blood of patients with carcinoma. The administration of cancericidal chemotherapeutic agents at the time of surgical removal of carcinoma to destroy any tumor cells existing as emboli was suggested by Cruz, McDonald, and Cole.5 Mechlorethamine (nitrogen mustard) and Thio-TEPA (triethylenethiophosphoramide) have been shown by Cole and his group6 to be markedly effective in reducing the incidence of tumor cell "take" when given to animals having Walker 256 carcinosarcoma cell suspensions injected into the portal vein. The clinical use of cancericidal agents at the time