Sjögren's syndrome (SS) is a systemic as well as an organ-specific autoimmune disease, characterized by destructive lymphocytic infiltration of the salivary and lacrimal glands. We divided SS patients into three stages: stage I is glandular SS, stage II is extraglandular SS, and stage III is extraglandular SS with lymphoid malignancy. The lymphoaggressive nature of the disease appears to lead SS patients from stage I to II and from stage II to III. However, stage III patients made up only 5% of SS patients. Many patients remain stable in stages I or II for as long as 10 or 20 years. Therefore, we can assume that there are factors which trigger patients in stages I or II to progress to stages II or III and that only those patients who have such factors progress from stages I or II to stages II or III, respectively. Accumulation in the salivary glands or in the peripheral blood of B cells which have rearrangement of the RF-related germline gene Vg or over-expression of the bcl-2 gene in the lymphoepithelial lesion might be included among these factors.