Abstract: With repeated exposure of BALB/C mice to hypobaric hypoxia,the tolerance time of the mince in the first run of exposure was 17.3 min in average and those of the subsequent 2nd,3rd and 4th runs were 3,6 and 7 times longer than that of lst run respectively,the animals'survival times in hypobaric chamber and after cyanide intoxication were 26 and 2.6 times longer respctively than that of the control without exposure to hypoxia.These results indicute that the BALB/C mices tolerance to hypoxia is significantly increased through acute and repetitive exposure to hypoxia.

Key words: repeated hypoxia, hypobaric chamber, cyanide intoxication, BALB/C mice