Primary Sjögren's syndrome (1 degrees SS) has been considered as a privileged model for the study of autoimmunity and B-cell neoplasia. Previous and recently accumulated information have reinforced this view. The given higher incidence of non-Hodgkin's lymphoma (NHL) in 1 degree SS patients, the presence of circulating monoclonal immunoglobulins, the detection of uniform immunoglobulin gene rearrangements and monoclonal B-cell expansions in the lymphocytic infiltrates of salivary gland, the increased levels of circulating CD5 positive B-cells and the association of these cells with the presence of monoclonal immunoglobulins from 1 degree SS, and finally the finding of shared cross reactive idiotypes on monoclonal immunoglobulins from 1 degree SS and B-cell malignancies, all provide evidence of common pathogenetic links between benign and malignant lymphoproliferation.