Objectives: To investigate the pattern of antibiotic use in 5 childrens hospitals in China over a 6-year period.Methods: The ATC/DDD (ATC code-J01) and DU 90% methodologies were used.Antibiotic use data was expressed in numbers of DDD/100 bed-days for inpatients and DDD/100 patient-days for outpatients.Results: In 5 childrens hospitals, 98 different systemic antibiotics were used.The overall consumption of antibiotic drugs of inpatients was 43-68 DDD/100 bed-days and of outpatients 29-43 DDD/100 patient-days.The top antibiotic drug used was Macrolides in inpatient department and third-generation cephalosporins in outpatient department.Conclusion: The ATC/DDD methodology provided delineation and interpretation of antibiotic usage pattern in the childrens hospitals.