The authors report on 2 patients with biliary atresia in whom pulmonary hypertension (PH) developed in the long-term follow-up after hepatoportoenterostomy. Both had portal hypertension and had undergone distal splenorenal shunt. Dyspnea developed around 14 to 15 years of age. Cardiac catheterization showed pulmonary artery pressure (PAP) of 99/37 (58) and 67/32 (48) mm Hg, respectively, which did not respond to vasodilators. One patient suffered from respiratory tract infection followed by right heart failure and subsequent death at 20 years of age. Postmortum histological findings exhibited severe thickening of the pulmonary artery wall. PH may grow insidiously even after successful hepatoportoenterostomy. Careful monitoring of PAP and hemodynamic response of PAP to vasodilators is essential for evaluating the reversibility of PH and making treatment decisions.