Objective     To investigate the possibility of tetracycline for lung volume reduction by fibrobronchoscope.       Methods     Five adult mongrel dogs were anesthetized and fibrobronchoscope was inserted to the subsegmental bronchi through mouth. CRE sacculus dilation catheter was put into local lung inflate sacculus. The suspension of 5% tetracycline was administered to anesthetized dogs. Atrophic constitution of local lung was detected by roentgenographic examination at 2

nd

4

th

8

th

12

th

week and type Ⅰ

Ⅱ collagens were detected by histopathologic methods at 12

th

week after tetracycline application.       Results     Procedure of operation was successful without technical difficulty

no dogs dead

and no complications happened. Lung tissue of high density was found at 12

th

week by CT

but no inflammatory changes. Under microscope

scar tissue was seen

indicating obstructive tissues lost the normal lung structure and formed dense fibrous tissues. Type Ⅰ collagen was positive and type Ⅱ collagen was negtive in lung tissue.       Conclusion     Operative procedure through fibrobronchoscope to administer tetracycline is easy

with the advantages of less trauma

few complications so that it can be used in lung volume reduction.