Gold thioglucose-induced hypothalamic obesity caused a higher altitude convulsion threshold and a decrease in the time to altitude convulsion. The average altitude convulsion threshold for the obese mice was 151 torr (38,500 ft). In contrast, the average value for the controls was 131 torr (41,500 ft). It was also observed that at 206 torr (32,000 ft), the average time until altitude convulsion of the obese mice was 69 s; at 179 torr (35,000 ft), 27 s; at 141 torr (40,000 ft), 17 s; at 111 torr (45,000 ft), 10 s; at 87 torr (50,000 ft), 9 s; and at 69 torr (55,000 ft), 8 s. On the other hand, the average control time until altitude convulsion at the above-mentioned altitudes was 97, 37, 26, 11, 9, and 8 s, respectively. Moreover, the average accumulation of fat between pleura and lungs in obese mice was 154 (Table I) or 181 mg (Table II), while the value of the control group was only 72 to 67 mg. Such an increase of fat accumulation in the thoracic cage could decrease the tidal volume. The altitude convulsion threshold and the time until altitude convulsion might thus be changed. The time until altitude convulsion may be regarded as a convenient objective measure of altitude tolerance in mice.