This study surveyed the pattern of inpatient antibiotic use in five Chinese children's hospitals between 2002 and 2006, focusing on the antibiotics accounting for 90% of the volume utilised as well as the level of adherence to guidelines. The Anatomical Therapeutical Chemical Classification/Defined Daily Doses (ATC/DDD) and the drug utilisation 90% (DU90%) methodologies were used. In October 2004, national antibiotic guidelines were issued that divided antibiotics into non-restricted, restricted and special use grades. In five children's hospitals, a total of 56 different systemic antibiotics were used during the study period. Antibiotics that could be injected accounted for 59.0-99.8%. beta-Lactam antibacterials (ATC codes J01C and J01D) were the most used subgroups. The numbers of antimicrobial agents and non-restricted antibiotics within the DU90% segment were 11-20 and 5-9, respectively. The proportion of non-restricted antibiotic consumption was ca. 40% in 2006 in four hospitals, which varied among hospitals during the period 2002-2005. There was considerable variation both in the pattern and amount of antibiotics used in the five hospitals, with amoxicillin/clavulanic acid, cefuroxime and cefazolin being the most commonly used substances. We also observed a decrease in the ranks of some restricted and special use antibiotics after the guidelines were issued in one hospital. The DU90% profiles were proven to be useful in studying the pattern of antibiotic use in hospitals. Finally, the study observed the effectiveness of guidelines for antibiotic use in some hospitals, although injectable antibiotics were widely used in children's hospitals in China. (C) 2008 Elsevier B. V. and the International Society of Chemotherapy. All rights reserved.