The work of three groups of investigators on the therapeutic effects of the nitrogen mustards was recently summarized.1The first clinical application of these compounds was initiated by Gilman, Goodman and others,2who administeredtris(β-chloroethyl) amine hydrochloride intravenously to a group of 6 patients in the terminal stages of a variety of neoplastic diseases. They observed a striking effect on hemopoietic tissue including the regression of lymphadenopathy in a case of lymphosarcoma. Independently in Chicago we initiated a clinical investigation of another nitrogen mustard, methyl-bis(β-choloroethyl) amine hydrochloride,3on patients with neoplastic diseases of the hemopoietic system on whom prolonged observation as to the therapeutic efficacy of the drug could be made. MATERIAL AND METHODS The chemistry of this drug has been discussed in detail elsewhere.4When placed in aqueous solution it undergoes a series of transformation, of which the first transformation product, an