The incidence of lower urinary tract infection in 120 women with rheumatoid arthritis and secondary Sjögren's syndrome was evaluated retrospectively. Thirty one patients (26%) had secondary Sjögren's syndrome. Recurrent urinary tract infection was significantly more common in these patients (11/31) than in patients without Sjögren's syndrome (4/89). Habitual leucocyturia was also more common in patients with secondary Sjögren's syndrome (18/31) than in patients with rheumatoid arthritis without Sjögren's syndrome (8/89). Of seven patients with vaginal sicca symptoms, six had recurrent urinary tract infection. Urinary 24 hour mucopolysaccharide excretion in 20 patients with Sjögren's syndrome was similar to the excretion in 10 patients without Sjögren's syndrome. These results show that recurrent urinary tract infection is significantly more common in women with rheumatoid arthritis and secondary Sjögren's syndrome. A local deficit in protective urinary mucosal secretion or other immune mechanisms may be responsible for this susceptibility.