For the chemotherapy of tuberculosis with kanamycin, it appears most important to delay the emergence of kanamycin resistance in Mycobacterium tuberculosis and, for the purpose, it appears at present to be most useful to utilize kanamycin with other known antituberculous drugs in view of our knowledges concerning with this problem. It is the purpose of the present paper to concern with the problem what a kind of combination of antituberculous drugs with kanamycin is most effective for delaying the emergence of kanamycin resistance in M. tuberculosis.