Objective:To investigate the effects of Shuang huang lian on the expression of basic fibroblast growth factor (bFGF) in the lung tissue from rats repeatedly infected with mycoplasma pneumoniae (MP). Methods:Made a rat MP infection model by infecting rats with MP for 9 times during a period of 24 weeks with a technique of ultrasonic nebulizing inhalation and treated the rats with Shuang huang lian by peritoneal injection. Then immunohistochemical stain was performed with bFGF monoclone antibody and the results were quantitatively analyzed. Results: ①MP polymerase chain reaction (PCR) tests showed positive results in the bronchoalveolar lavage fluid (BALF ) from all of the MP infected rats (n=4) while they were all negative in BALF from the control animals (n=4, P<0.05) and in BALF from those rats both infected with MP and, at the same time, treated with Shuang huang lian (n=4, P<0.05). Bacterial cultures of the bronchial and lung tissue were negative in all three groups. The observation with transmission electron microscope found that the interalveolar septa were widened with increased amount of collagen in the MP infected rats while there were no obvious abnormalities in the other two groups. ②Strong positive stain of bFGF protein was found in the plasma of bronchial epithelia, in the muscle of bronchi and pulmonary arteriole, and in the plasma of alveolar macrophages in the lung tissue from the MP infected animals with the integral optical densities being 41.62±4.33 (n=4) which was significantly higher than the values of control group (10.19±2.93, n=4, P<0.05) and of the group with MP infection plus Shuang huang lian treatment (12.74±3.74, n=4, P<0.05). Conclusion:Shuang huan lian could inhibit the overexpression of bFGF in the lung tissue of rats with MP infection, which may be helpful for the prevention and treatment of pulmonary interstitial fibrosis caused by the repeated MP infection.