Cross-linked fibrin degradation products (XDP) were measured with a highly sensitive and specific ELISA in 21 patients with essential mixed cryoglobulinemia (EMC) and in 16 controls. Patients had significantly increased levels of XDP, together with abnormalities in routine coagulation tests. Moreover, XDP were higher in patients with more severe disease. These results support the hypothesis that EMC patients have a chronic disseminated intravascular coagulation (DIC), and underline the significance of XDP measurement in the evaluation of these patients.