N,N’N’-triethylenethiophosphoramide (ThioTEPA) is a cancer chemotherapeutic member of the alkylating agent group, now in use for over 50 years. It is a stable derivative of N,N’,N’’- triethylenephosphoramide (TEPA). The radiomimetic action of thiotepa is believed to occur through the release of ethylenimine radicals which, like irradiation, disrupt the bonds of DNA. One of the principal bond disruptions is initiated by alkylation of guanine at the N-7 position, which severs the linkage between the purine base and the sugar and liberates alkylated guanines. Thiotepa has been used in the palliation of a wide variety of neoplastic diseases. The more consistent results have been seen in: adenocarcinoma of the breast, adenocarcinoma of the ovary, superficial papillary carcinoma of the urinary bladder and for controlling intracavitary effusions secondary to diffuse or localized neoplastic diseases of various serosal cavities.