Since vitamin K2 (VitK2) syrup prophylaxis has become a routine measure for neonates and young infants, the incidence of vitamin K deficiency (VitK-D) in infancy has markedly decreased. However, we recently experienced 2 infantile cases of VitK deficiency, in whom intracranial hemorrhage (ICH) was the first clinical sign of CMV hepatitis. Case 1 is a breast-fed boy who received VitK2 syrup orally at birth and at the age of 1 month. He did not suckle well and developed a generalized tonic convulsion twice at the age of 8 weeks. Case 2 is a mixed-fed boy who also received VitK2 syrup twice but developed vomiting and drowsiness at the age of 4 months. In both cases, laboratory tests showed anemia, leukocytosis, liver dysfunction with cholestasis, and coagulopathy, consistent with VitK-D abnormality. Their serological analyses showed that cytomegalovirus (CMV) IgG and IgM were both positive. In case 1, CMV DNA was positive, as judged by the PCR method. In case 2, CMV antigenemia was positive. Hence we diagnosed these two patients as having VitK-D ICH caused by CMV hepatitis with cholestasis. CMV hepatitis is a risk factor of VitK-D ICH.