<正> The effects of administering similar doses of some simple alkylating agents to rats by differentregimens have been compared.Two of the compounds were methylating agents,nitrosodimeth-ylamine and azoxymethane;two were ethylating agents,nitrosodiethylamine and azoxyethaneand nitrosomethylethylamine was both a methylating and an ethylating agent.The treatmentsgave rise to tumors in almost all treated rats.The results indicate the importance ofpharmacoki-netics in determining which organs are the targets of the alkylating carcinogens.1989 AcademicPress.Inc.