Anti-SS-A/Ro antibody (SS-A) and anti-SS-B/La antibody (SS-B) are important serologic markers in the diagnostic criteria for Primary Sjögren's syndrome (SS). Although anti-centromere antibody (ACA)-positive SS is frequently experienced, ACA is not included in these criteria. The purpose of this study was to identify the clinical features of ACA-positive SS and discuss the usefulness of ACA in diagnosing SS. Forty-five patients with SS were divided into the following three groups: SS-A only-positive group (n = 17), SS-A and SS-B both-positive group (n = 18), and ACA only-positive group (n = 10). As a control, 54 patients without SS who were negative for antinuclear antibodies were also evaluated. The following items were compared among groups: Saxon's test, unstimulated whole salivary flow (UWSF), salivary gland scintigraphy (SGS), histopathologic examination of the minor salivary glands, Schirmer's test, and fluorescein staining of the cornea. In the ACA only-positive group, Saxon's test was 0.21 ± 0.26 g/2 min (mean ± SD) and UWSF was 0.16 ± 0.25 ml/10 min (mean ± SD), showing a significant decrease in salivary secretion (p < 0.05; vs. non-SS). On SGS, accumulation and disappearance of (99m)TcO (4) (-) were significantly decreased (p < 0.05; vs. non-SS). Histopathologic examination showed moderate or severe lymphocytic infiltration and tissue destruction in all cases, similar to that in the SS-A- and/or SS-B-positive groups. Schirmer's test and fluorescein staining were positive in 60% and 80%, respectively. Impaired lacrimal secretion and keratoconjunctivitis sicca were similar to those in SS-A- and/or SS-B-positive groups. These results suggest that ACA is an autoantibody reflecting impairment in the salivary and lacrimal glands and may be a useful serologic marker for SS.