Introduction: Diabetes can affect organs including the oral mucosa. There is a disagreement about the prevalence of oral mucosal disease in diabetic patients. We therefore decided to investigate more about that. The aim of this study was to determine the prevalence of soft tissue pathologies by assessing burning mouth and xerostomia in diabetic patients on the basis of type of diabetes and control status of diabetes. Methods: This descriptive, analytic study was done by visiting 486 known diabetic patients who were referred to the Endocrine Clinic in summer of 2005. Their demographic information with history of systemic diseases accompanied by the amount of HbAIC and duration of disease was recorded in their questionnaire. Diagnosis of oral lesions was done by clinical examination. Burning mouth was assessed by visual analog scale in persons who suffered and subjective xerostomia was evaluated by standard questionnaire. Data collection was done by software SPSS 10, and statistical analysis was done by X2 and logistic regression test. Results: In this study, 34 patients were type I and 434 were type II patients with mean age of 47.84±9.77 years. Frequency of all candidasis lesions was 15.4% which included denture stomatitis 5.3%, angular cheilitis 4.1%, median rhomboid glossitis 1.5%and papillary atrophy of tongue 4.5%. Frequency of non-candidal lesions was 20.1%, which included fissured tongue 10.5%, geographic tongue 7.9% and lichen planus 1.7%. 6.2% of patients suffered from glossodyna. 15.6% of patients had xerestomia. By logistical regression test, we found that type of diabetes affects denture stomatitis, angular cheilitis, tongue atrophy and amount of HbA1c. Conclusion: All of the pathologies were greater in type I than type II diabetes patients. Level of HbA1c had an important role in appearance of oral lesions and level changes can cause problems in the mouth. Thus, patients should maintain their oral hygiene and control their glucose regularl