Interleukin7 (IL)-17-mediated immune response has been shown to play a critical role in inflammation-associated disease.However, its role in the pathogenesis of chronic hepatitis B virus (HBV) in paediatric patients remains unknown.We investigated the frequency of T helper type 17 (Th17) cells and evaluated the association between the Th17 and clinical characters in paediatric patients with chronic hepatitis B (CHB).The frequency of Th17 cells was detected by flow cytometry analyses from 65 paediatric patients with CHB and nine healthy controls.The degree of hepatic inflammation was graded using the histological activity index (HAI).