The long-term histological outcome after pediatric liver transplantation (OLT) is not yet fully understood. De novo autoimmune hepatitis, consisting of histological chronic hepatitis associated with autoantibody formation and allograft dysfunction, is increasingly recognized as an important complication of liver transplantation, particularly in the pediatric population. In this study, 158 asymptomatic children with 5-year graft survival underwent protocol liver biopsies(113, 135, and 64 at 1, 5, and 10 years after OLT, respectively). Histological changes were correlated with clinical, biochemical, and serological findings. All patients received cyclosporine A as primary immunosuppression with withdrawal of corticosteroids at 3 months post OLT. Normal or near-normal histology was reported in 77 of 113 (68%), 61 of 135 (45%), and 20 of 64 (31%) at 1, 5, and 10 years, respectively. The commonest histological abnormality was chronic hepatitis (CH), the incidence of which increased with time[25/113 (22%), 58/135 (43%), and 41/64 (64%) at 1, 5, and 10 years, respectively) (P< .0001)]. The incidence of fibrosis associated with CH increased with time [13/25 (52%), 47/58 (81%), and 37/41 (91%) at 1, 5, and 10 years, respectively)(P < .0001)]. The severity of fibr- osis associated with CH also increased with time, such that by 10 years 15%had progressed to cirrhosis. Aspartate aminotransferase(AST) levels were slightly elevated in children with CH (median levels 52 IU/L, 63 IU/L, and 48 IU/L at 1, 5, and 10 years, respectively), but this did not reach statistical significance compared with those with normal histology. On multivariate analysis, the only factor predictive of chronic hepatitis was autoantibody positivity (present in 13%and 10%of children with normal biopsies at 5 and 10 years, respectively, and 72%and 80%of those with CH at 5 and 10 years, respectively)(P < .0001). Four children with CH and autoantibodies, who also had raised immunoglobulin G (IgG) levels and AST greater than 1.5x normal fulfilled the diagnostic criteria for de novo autoimmune hepatitis(AIH). Another two were found to be hepatitis C positive. No definite cause for CH could be identified in the other cases. In conclusion, chronic hepatitis is a common finding in children after liver transplantation and is associated with a high risk of developing progressive fibrosis, leading to cirrhosis. Standard liver biochemical tests cannot be relied on either in the diagnosis or in the monitoring of progress of chronic allograft hepatitis. In contrast, the presence of autoantibodies is strongly associated with the presence of CH. The cause of chronic hepatitis in transplanted allografts is uncertain butmay be immunemediated, representing a hepatitic form of chronic rejection. The long-term histological outcome after pediatric liver transplantation (OLT) is not yet fully fully understood. De novo autoimmune hepatitis, consisting of histological chronic hepatitis associated with autoantibody formation and allograft dysfunction, is increasingly recognized as an important complication of liver transplantation, particularly in the pediatric population. In this study, 158 asymptomatic children with 5-year graft survival underwent protocol liver biopsies (113, 135, and 64 at 1, 5, and 10 years after OLT, respectively). Histological changes were correlated with clinical, biochemical All of the patients received cyclosporine A as primary immunosuppression with withdrawal of corticosteroids at 3 months post OLT. Normal or near-normal histology was reported in 77 of 113 (68%), 61 of 135 (45%), and 20 of 64 (31%) at 1, 5, and 10 years, respectively. The commonest histological abnormality was chronic hepatitis (CH), the incidence of which increased with tim (25%), 58/135 (43%), and 41/64 (64%) at 1, 5, and 10 years, respectively) (P <.0001)]. The incidence of fibrosis associated with CH increased with time [13/25 (52%), 47/58 (81%), and 37/41 (91%) at 1, 5, and 10 years, respectively) severity of fibr- osis associated with CH also increased with time, such that by 10 years 15% had progressed to cirrhosis. Aspartate aminotransferase (AST) levels were slightly elevated in children with CH (median levels 52 IU / L, 63 IU / L , and 48 IU / L at 1, 5, and 10 years, respectively), but this did not reach statistical significance compared with those with normal histology. On multivariate analysis, the only factor predictive of chronic hepatitis was autoantibody positivity (present in 13 % and 10% of children with normal biopsies at 5 and 10 years, respectively, and 72% and 80% of those with CH at 5 and 10 years, respectively) (P <.0001). Four children with CH and autoantibodies, who also had raised immunoglobulin G (IgG) levels and AST than than 1.5x normal fulfilled the diagnostic criteria for de novo autoimmune hepatitis (AIH). Another two were found to be hepatitis C positive. No definite cause for CH could be identified in the other cases. finding in children after liver transplantation and is associated with a high risk of developing progressive fibrosis, leading to cirrhosis. either in the diagnosis or in the monitoring of progress of chronic allograft hepatitis. In contrast, the presence of autoantibodies is strongly associated with the presence of CH. The cause of chronic hepatitis in transplanted allografts is uncertain butmay be immunemediated, representing a hepatitic form of chronic rejection.