We investigated noninvasive follow-up markers for histologic liver fibrosis and portal hypertension (PH) in patients with biliary atresia after successful portoenterostomy (PE). Among children with bilirubin <20 µmol/L after PE (n = 39), Metavir fibrosis stage was evaluated at PE and in follow-up protocol liver biopsies (n = 83). PH was defined as endoscopically confirmed esophageal varices or thrombocytopenia associated with splenomegaly. The accuracy of liver biochemistry and stiffness in detecting liver fibrosis and PH was analyzed by the area under the receiving operating characteristic curve (AUROC) and multiple regression models. During a median native liver survival of 8.3 years (interquartile range 2.5-10.8 years), cirrhosis (Metavir F4) had developed in 51% of patients and PH in 54% of patients. Cirrhosis was equally common in all age tertiles of 1.2-2.1 years (n = 10/27), 3.9-5.8 years (n = 12/28), and 9.0-14 years (n = 12/28). In the two oldest age tertiles, histologic liver fibrosis had progressed further in patients with PH than without PH (P < 0.001). PH was accurately predicted by the aspartate aminotransferase-to-platelet ratio index (APRI) (cutoff, 0.70; AUROC, 0.92), bile acids (cutoff, 49 µmol/L; AUROC, 0.91), and liver stiffness (cutoff, 16.9 kPa; AUROC, 0.89; P < 0.001 each) across all age tertiles. Liver stiffness was the most accurate predictor of cirrhosis overall (AUROC, 0.82; P < 0.001), whereas bilirubin was >11 µmol/L in the youngest tertile (AUROC, 0.91; P < 0.001), bile acids was >80 µmol/L in the middle tertile (AUROC, 0.81; P = 0.009), and liver stiffness was >24 kPa in the oldest age tertile (AUROC, 0.96; P = 0.002). Conclusion: After successful PE, development of PH associates with progression of liver fibrosis and can be accurately detected by APRI and stiffness. Liver stiffness most accurately identified cirrhosis in older children, whereas biochemical markers of cholestasis closely reflected histologic cirrhosis in younger children.