Purpura fulminans must be treated as an emergency in internal medicine and dermatology. Its characteristic features are the sudden development of progressively enlarging haemorrhagic skin necrosis, severe disseminated intravascular coagulation with consumption of anticoagulant factors, and signs of shock. Purpura fulminans can be classified into a neonatal form with inherited protein C deficiency and an acquired type for which multiple causes are known. Clinically it is characterized by massive ecchymosis with haemorrhagic blebs and acral necrosis. Histologically the lesions show widespread extravasation of erythrocytes and thrombosis of small vessels. Thrombocytopenia, decrease of coagulation factors, the presence of fibrinogen split products and fragmented erythrocytes in the blood smear help to confirm the diagnosis. The therapy includes fresh-frozen plasma, heparin, antibiotics and surgical debridement of necrotic areas. It is important to recognize the disease promptly because the mortality rate is about 30-40% and only quick intervention helps to save the life of the patient.