Budd-Chiari syndrome (BCS) caused by hepatic venous outflow obstruction may result in portal hypertension and the development of intrahepatic collaterals that bypass the obstruction. Spontaneous intrahepatic portosystemic venous shunt (SIPSVS) is uncommon and may be associated with portal hypertension. SIPSVS is extremely rare in patients with BCS and has not been well documented. We report a case of SIPSVS in a 42-year-old woman with BCS caused by membranous obstruction and chronic thrombosis in the inferior vena cava (IVC). A direct vascular communication between the left portal vein and IVC was confirmed by sonography and a computed tomography angiography scan. The patient underwent successful percutaneous balloon angioplasty of the IVC. Surgical or endovascular treatment for SIPSVS was not carried out because the patient was asymptomatic and remained asymptomatic in terms of encephalopathy at a 1-year follow-up.