The history, ocular and oral clinical features, and histopathology of Sjögren's syndrome are described. Primary Sjögren's syndrome is defined when only the ocular and oral components are present, while the secondary form refers to the association with a connective tissue disorder, especially rheumatoid arthritis, or other illness such as AIDS, hepatitis C infection, or biliary cirrhosis. Sjögren's syndrome is a common, but often overlooked disorder. Patients with severe disease run a forty-times risk of developing lymphoma usually of the B cell type.