The total average value ( n du t(CFU)/ m -3 )of indoor air borne microbial number of Chinese Great Wall Station, Antarctica investigated in Feb. 1994 was 660.2 m -3 , with variation range <26.2~ 7231.2 m -3 . Generally the number of indoor air borne microbes was 233.0 m -3 on the average except under particular circumstances. There were higher mildew detection rates and mildew number/total microbial number in some sampling sites. The variation in the indoor air borne microbial number was related closely with human activities and environmental hygienical conditions. Generally speaking, the indoor air quality of the Great Wall Station was fairly good. But it still need good hygienical habits and more attention to further improve the indoor air conditions and the whole circumstance conditions of the Great Wall Station. Tab 3, Ref 8