Objective To study the relationship between erythromycin sensitivity and drug-resistance gene in Mycoplasma pneu-moniae(Mp).Methods In 46 erythromycin-resistant MP clinical isolates,domain Ⅴ of 23S rRNA was amplified by polymerase chain reaction(PCR),followed by direct automatic sequencing method.The DNA sequences were compared to find molecular mecha-nisms of drug resistance.Results Among the 46 erythromycin-resistant Mp clinical isolates,44(95.65%)harbored an A-to-G tran-sition mutation at position 2063 in the 23S rRNA gene and 2(4.35%)harbored an A-to-G transition mutation at position 2064,but no A-to-C transition mutation at position 2063 and C-to-G/A transition mutation at position 2617 were detected.Conclusion E-rythromycin-resistant of Mp clinical isolates were closely related to A-to-G transition mutation at position 2063/2064 in domain Ⅴof 23S rRNA genes and the most important was the A2063G transition mutation.Rapid and accurate identification of the genetic mutations in domain Ⅴ of 23S rRNA may be help to diagnose the infection of Mycoplasma pneumoniae,provide the drug-resistant information,and instruct the application of antibiotics reasonably and effectively.