Objective To evaluate the effect of azithromycin on mycoplasmal pneumonia (MP).Methods We divided 90 MP cases into azithromycin and erythromycin treatment groups. In azithromycinThe pyretolysis time, cough improvement time, the disappearing time and the mean length of hospitalization of azithromycin group were shorter than that of erythrornycin group. The local ache, stomach and intestinal tract adverse reaction, and damage of hepar function were less than these in erythromycin group. ConclusionAzithromycin is an effective and safe drug to MP.