Liver biopsy is the gold standard for detection of the severity of liver fibrosis and cirrhosis. However, it is limited by invasiveness, complications, sampling error, and variability in pathological interpretation. On the other hand, the aspartate aminotransferase to platelet ratio index (APRI) is a good estimator of hepatic fibrosis. This study aims to investigate the association between APRI value and severity of liver fibrosis. Blood samples were taken from 52 patients with the age of 2 months to 18 years who were referred to the Pediatric Gastroenterology Ward of Nemazee Teaching Hospital with diagnosis of chronic liver disease. The aspartate aminotransferase (AST) level and platelet counts 1 week before the taking of liver biopsy were determined. Closed biopsy of the liver through the skin was performed, and the severity of hepatic fibrosis was interpreted according to the Meta-analysis of Histological Data in Viral Hepatitis (METAVIR) staging system. The APIR ratio was calculated for all patients, and the relationship between APIR and hepatic fibrosis was determined using Spearman's correlation coefficient test. Our patients were categorized into four liver disease groups including cholestatic, hepatitic, genetic/metabolic, and unknown causes. Mean APRI value of 3.4 was significantly (P = 0.046) correlated with advanced fibrosis (F 3 , F 4 ) only in the patients with genetic/metabolic group. Our data suggest that APRI may be used as a simple test to evaluate and follow up the liver fibrosis in children with genetic/metabolic liver diseases, but in other groups, it needs to do some studies with higher sample size.