We investigated oral health of chronic kidney disease (CKD) patients at predialysis state. The hypothesis was that diabetic nephropathy affects oral health more detrimentally than other CKD patients due to the known risk diabetes presents in this regard. We expected worse oral health and particularly poor periodontal health among the diabetic patients. A cross-sectional study was conducted in the Helsinki University Central Hospital, Finland, on 148 patients with different kinds of kidney disease at predialysis state. Data from medical records, clinical oral examination, saliva, and mucosal yeast counts were analyzed and compared between the disease groups. Of the patients, 53 (36%) had diabetic nephropathy (29 patients with type 1, 24 patients with type 2 diabetes). Compared with other CKD patients, diabetic patients had poor glycemic control as expected (mean HbA(1C) 8.0% vs 5.9%, p < 0.01). Diabetic patients also had more dental caries (mean number of carious teeth 5.1 vs 3.1, p < 0.01) and lower salivary flow rates than other CKD patients (stimulated salivary flow 1.2 ml/min vs 1.6 ml/min, p < 0.05). No difference between groups was observed in periodontal health and yeast counts. In conclusion, diabetic nephropathy patients indeed had worse dental health in comparison to CKD group. However, contrary to our expectation, diabetic nephropathy did not seem to affect periodontal health more severely than the other kidney diseases.