A 50-day-old girl with swelling and ecchymosis of right hand dorsum after DTP vaccination on ipsilateral deltoid area was referred to the pediatric infectious disease outpatient unit with a presumed diagnosis of gangrenous cellulites. Physical examination and laboratory evaluation revealed intramuscular bleeding as a result of vitamin K deficiency. We would like to emphasize the importance of both vitamin K prophylaxis in the newborn to prevent hemorrhagic disease of the newborn and of the education of persons administering vaccines about this very basic aspect of pediatrics for early recognition.