The present investigation was designed to study caries and periodontal conditions in a selected group of patients with primary Sjögren's syndrome (1oSS). Twenty-one patients, 20 females and 1 male aged 44-75 years (mean 64 years), with recently diagnosed 1oSS constituted the study population. As a control group, 21 patients matched according to sex and age were randomly selected from patients at one clinic in the Public Dental Service. Clinical examinations including registrations of dental caries, restorations, and periodontal conditions were performed. Unstimulated and stimulated salivary secretion rates were recorded. The 1oSS group had a mean number of 16.4 +/- 8.9 and the control group 17.1 +/- 8.4 natural teeth. The 1oSS patients had significantly more DF crown surfaces (63 +/- 25.8 vs 43 +/- 21.3) and more inactive root caries (4.4 +/- 5.4 vs 0.5 +/- 0.9) than did the control patients. No significant differences were found between the groups in the periodontal conditions. The mean value of the unstimulated salivary secretion rate was 0.09 +/- 0.16 ml/15 min in the 1oSS group and 3.33 +/- 2.81 ml/15 min in the control group. The stimulated secretion rate was 0.16 +/- 0.15 ml/min and 1.47 +/- 0.64 ml/min respectively. This study confirms results from other studies that patients with 1oSS face a high risk of developing both coronal and root caries due to xerostomia. The periodontal conditions are similar to those found in patient groups in general dentistry.