The criteria for diagnosis of SS remain controversial, and several sets of diagnostic criteria have been proposed. On one hand, we have used a stringent set of criteria (termed the San Diego criteria) that requires evidence for an autoimmune process associated with destruction of salivary and lacrimal gland tissues. At the other extreme, several groups (including the Copenhagen and EEC Study group) have based their diagnostic criteria on clinical findings of dry eyes and mouth with no absolute requirement for gland biopsy or presence of autoantibodies. The EEC study group believe that the San Diego criteria identify only the tip of the iceberg--namely, those patients with full-blown disease--and ignore those patients with milder forms of SS. Until the underlying pathogenesis of SS is known, we suggest the continued use of the San Diego criteria for classification of SS, because it identifies a group of patients with serologic and histologic evidence for a systemic autoimmune process in association with their sicca symptoms. In patients lacking such evidence for an autoimmune process, we suggest the classification "sicca syndrome" or "dry mouth syndrome." This will allow the clinicians and clinical trials to focus on a more homogeneous group of SS patients who may share a common pathogenesis, treatment response, and prognosis. Also, patients lacking evidence of an autoimmune role in pathogenesis can be reassured, and other causes for their sicca symptoms can be investigated. Further, in the United States the particular diagnosis codes may have implications in obtaining insurance and other medical benefits. Thus, classification criteria involve not only future epidemiologic studies but also economic considerations for the individuals who are given a particular diagnostic code.