In the present study, the experiment was made to observe the change of the blood sugar levels in the process of general anesthesia, subjecting the rabbits to the light or deep inhalation anesthesia with ether or methoxyflurane by the non-rebreathing system. The blood sugar level was measured by the method of Somogyi and Nelson. The results are summarized as follows; 1. The blood sugar level of the normal rabbit was 112. 04±9.88 mg%. 2. The blood sugar level in the initial stage of the light ether anesthesia was significantly increased, and slight decrease was observed in the beginning of the deep anesthesia. 3. In the ether anesthesia group, the sugar level increased gradually when deep anesthesia was induced. 4. Anesthesia with methoxyflurane produced a similar pattern of the blood sugar as in the ether group, with no significant difference between ether and methoxyflurane anesthesia.