Cryoglobulins are immunoglobulins or immune complexes which precipitate at a temperature lower than 37 degrees C and redissolve when rewarmed. Cryoglobulins can be asymptomatic. When not, clinical features are in most cases cutaneous, renal or neurological. Cryoglobulinemia are associated with malignant haematological disorder, connective tissue disease or infection process especially infection with hepatitis C virus. In some case, no aetiology can be found, in theses cases cryoglobulinemia are called primary or essential cryoglobulinemia. For the last ten years it has been widely demonstrated that virus C infection causes the most part of essential cryoglobulinemia.