A 4-year-old boy underwent pulmonary testing for diagnosis of exercise-induced dyspnea and subsequent cyanosis. Findings demonstrated the presence of multiple pulmonary arteriovenous fistulas resulting in oxygen desaturation owing to shunting (PaO2, 44 mm Hg). Abdominal ultrasound, abdominal computer tomography, and mesenteric angiography revealed an extrahepatic portocaval fistula (PCF), absence of a patent portal vein, and no evidence of portal hypertension. Because these findings were consistent with hepatopulmonary syndrome (HPS), liver transplantation was initially considered. However, subsequent workup using cavofistulography revealed the presence of a hypoplastic portal vein that selective catheterization showed to be threadlike but patent. Based on this finding, a definitive diagnosis of a congenital PCF with hypoplasia of the portal vein (type 2 Abernethy malformation) was made and surgical ligation with transection of the fistula was performed at the age of 5. Treatment was successful without subsequent development of portal hypertension and pulmonary symptoms disappeared. Follow-up examination 4 years later showed that the boy was asymptomatic and that the intrahepatic portal system was patent with normal hepatopetal flow. This is the first reported case of HPS because of portal type 2 Abernethy malformation. Anatomical types of PCF and corresponding therapeutic options in case of HPS are discussed.