A 51-year-old woman with interstitial cystitis was referred for screening of autoimmune disease. She was positive for results of Schirmer and Saxon tests and for ss/A and ss/B antibodies. Autoantibodies to type 3 muscarinic acetylcholine receptor were detected in the patient's serum by Western blotting. We diagnosed her as having interstitial cystitis accompanying Sjögren's syndrome. To enable early treatment, interstitial cystitis should be considered when patients with Sjögren's syndrome complain of urinary symptoms.