A 4-week-old infant presented with a coagulation disorder resulting from a vitamin K deficiency. The vitamin K deficiency was caused by neonatal cholestasis due to biliary atresia. Jaundice, hepatomegaly and pale stools are the predominant presenting symptoms of biliary atresia, none of which were recognized in our patient before admission. However, the patient presented with bleeding caused by vitamin K deficiency. She was fully breastfed and had received adequate doses of vitamin K at birth and from the age of 1 week. In case of a hemorrhagic diathesis due to neonatal cholestasis, timely identification of treatable underlying disorders, in particular biliary atresia, is important because an early surgical intervention results in a better prognosis. Meticulous history taking and a thorough physical exam can be decisive for an early diagnosis and subsequent intervention.