Objective To evaluate the clinical efficacy and safety of injection azithromycin in the treatment of the acute bacteria pneumonia of infant. Methods A randomized controlled open trial was carried out. Erythromycin as a controll drug was compared the clinical efficacy and safety with azithromycin as a test drug. Results In azithro-mycin group,the clinical effective rate was 90.6% ;the fully recovered rate was 75.5%. While those of erythromycin group were 68.0% ,36.0% respectively. The incidence of adverse reaction was 9.3% and 30.4% respectively in two groups. Conclusion Injection azithromycin of new macrofides type is a kind of effective and safe anti-bacterial drug.