Cryoglobulinemia. Cryoglobulinemia is defined by the presence of a circulating cryoglobulin, a cold-precipitating immunoglobulin. The typing of this cryoglobulin is fundamental. Indeed, there are two subgroups: cryoglobulin type I and mixed cryoglobulins. The physiopathology and treatments are different in these two entities. Cryoglobulinemia type 1 is associated with an underlying monoclonal lymphoid B hemopathy, while mixed cryoglobulinemia (types II and III) emerge in quite varied antigenic stimulation situations, the most common being the hepatitis C virus. The intensity of the symptoms is very variable, many patients are asymptomatic. In symptomatic patients, the most frequently affected organs are the skin, the peripheral nervous system and the renal glomerulus. Few patients have visceral involvement that is life-threatening. The treatment always takes into account the intensity of the symptoms and the underlying pathology. In cryoglobulinemia type I, treatment of the underlying clone is essential. In type II, immunosuppressive therapy is most often associated with treatment of the cause, if identified.