A breast-fed boy, born to first-cousin parents, had been vomiting since birth; his general condition remained good until age 6 weeks when vomiting became more frequent, and his status suddenly worsened, with polypnea, shock, hypothermia, jaundice, presence of blood in urine, gastric juice, stool, and bleeding tendency during veno-punctures. There was an huge hepatomegaly and a splenomegaly. Hypoglycaemia, metabolic acidosis, severe blood coagulation disturbances, elevated liver enzymes, hypoalbuminemia, pointed to an acute liver failure. He was resuscitated with current supportive measures, and was given a wide spectrum antibiotherapy. Because serologic tests for syphilis were positive in the child and his mother, including the presence of specific IgM the infant was then given Penicillin G therapy only, which resulted in a complete recovery. One month later, a needle liver biopsy showed residual signs of hepatitis. Other possible infectious or metabolic causes of acute liver failure occurring early in life had been excluded.