The case reported here is of a 61-year-old woman diagnosed with hepatopulmonary syndrome. She had had severe hypoxemia for 5 years. In room air, her arterial oxygen tension was low, and although we anticipated that treatment with oxygen would increase it, the treatment failed to do so. Pulmonary perfusion imaging with Tc-99m-labelled macroaggregated albumin showed an arterio-venous shunt in the lungs. Blood tests and liver scanning with Tc-99m-labelled galactosyl human serum albumin showed abnormalities of liver function, and per-rectal portal scintigraphy with Tc-99m pertechnetate showed severe portal hypertension. Inspection of a biopsy specimen taken under ultrasonographic guidance showed primary biliary cirrhosis of Scheuer stage I. The causes of hepatopulmonary syndrome are unknown, but seem to include a decrease in hepatic functional reserve, portal hypertension, or other factors. The development of hepatopulmonary syndrome due to portal hypertension in this patient is of interest.