The discovery of a large patent ductus venosus resulted from radiological investigations in a 34-year-old man, a chronic alcoholic of low mental status. Splenoportal and inferior caval venograms were performed because of recent exacerbation of the neurological symptoms and electroencephalographic criteria of portacaval encephalopathy. Portal pressure was 8 mm Hg. A liver scan, a laparoscopy, and a liver biopsy were performed. They showed that the gland was atrophic with a microscopic appearance of alcoholic fibrosis, but without any nodular regeneration. The relationship between the fistula, the mental state, and the atrophic liver is discussed. Such a malformation appears to be very uncommon.