We analyzed patients with dry eye syndrome with regard to autoimmune conditions. A total of 116 patients with dry eye syndrome were divided into three groups: simple dry eye (SDE), i.e., dry eye with no circulating autoantibodies; autoimmune positive dry eye (ADE), dry eye with circulating autoantibodies; and Sjogren's syndrome (SS), dry eye associated with Sjogren's syndrome. Schirmer test showed values of 3.0 +/- 2.2 mm in SDE, 3.1 +/- 2.0 mm in ADE, and 2.4 +/- 2.3 mm in SS reflecting the inadequacy of this test in differentiating among the groups. However, Schirmer test with nasal stimulation showed values of 19.1 +/- 12.4 mm in SDE and 16.4 +/- 10.9 mm in ADE, which were significantly higher than the 7.0 +/- 6.6 mm found in SS (p < 0.01). Moreover, ocular surface alterations evaluated by vital staining and brush cytology were significantly milder in SDE and ADE than in SS. SDE and ADE have less ocular surface abnormalities with good reflex tearing, whereas SS has less reflex tearing and more squamous metaplasia.