Objective: To determine the prevalence of mucosal alterations and oral lesions diagnosed at the School of Dentistry, Federal University of Amazonas, Manaus-Brazil. Materials and methods: Cross-sectional, descriptive and retrospective study, which analyzed the medical records of patients over 18 years of age from 2010 to 2013. Data were collected related to presence of soft tissue alterations, with emphasis on white-colored lesions, as well as variables such as age, gender, use of medications, systemic diseases and deleterious habits. The data were submitted to descriptive analysis and presented by average and standard deviation by means of tables. Results: 82 medical records were included, with prevalence of the female (60.98%) and mean age of 43.3 years. A total of 307 oral mucosa alterations were found and among these 27.69% consisted of white-colored lesions. Fordyce granules (35.37%)...