Objective The prescription of quinolones has been restricted for use in pediatric due to the adverse effects on cartilage development.The aim of this study was to investigate and compare the occurrence of quinolone resistance and the mutation of gyrA in clinical isolates of Escherichia coli from children and adults.Materials and Methods From October 2010 to December 2011,290 consecutive, non-repetitive isolates of E.coli were collected from three tertiary hospitals in Harbin.The sample consists of 163 isolates from adults and 127 from children.