Recently there can be seen a tendency to the successive use of a large amount of thiamine. Investigations have been made to know whether any symtom of thiamine deficiency will easily occur or not when the profuse administration of the vitamin is discontinued followed by the administration of insufficient amount of the vitamin, since the living body may be accustomed to the profuse administration of thiamine. To Uroloncha striata var. domestica sensitive to thiamine, 100 to 300 times as much as the requirement for thiamine were administered for a long period. After the administration, they were fed on thiamine insufficient diet, and the body weight as well as days of survival were observed. The results showed that no special difference was observed between the dosed group and the control which was not accustomed to the profuse administration of the vitamin. Contrary to the author's expectation, the profuse administration of thiamine did not cause any habituation to excessive vitamin metabolism.