Objective      To investigate the composition and drug sensitivity of mountain air micro-flora in the 3 districts along the Dian-Zang line.       Methods      Sunny slopes and shady slopes of same high altitude from 4 mountains at Shangri-La

Deqin and Markam districts were selected separately as sampling points. The air sampling was performed by plate natural sedimentation. After culture

bacterial and fungus was isolated and identified by TREK DIAGNOSTIC SYSTEMS LTD automated microbial identification system. Susceptibility testing was conducted by K-B method.       Results      A total of 591

446 and 292 strains of bacteria

and 30

33 and 16 strains of fungus were isolated from the 3 districts

separately. The total amounts of microorganism in shady slope were significantly larger than those in sunny slope (P＜0.05). Bacterium (95.0%) composed most of the air microorganism in the air from 3 high altitude districts

but fungus (5.0%) very less. There were more Gram-negative bacteria (56.0%) than Gram-positive bacteria (39.0%). And most microorganism was sensitive to commonly used antibiotics.       Conclusion      With the increase of altitude

the number of species and amount of bacterium gradually are decreased

the number of fungus species is decreased

but that at Deqin is higher than the other 2 districts. The drug sensitivity of the microorganism also gets higher with the high altitude. The composition and drug sensitivity of microbial flora in the air mountain along the Dian-Zang line districts are obtained

which is valuable in the prevention

diagnosis and treatment of infectious diseases.