Abstract There are no studies about pediatric oral mucosal diseases performed by dermatologists in Brazil. This study presents the casuistics of oral mucosal diseases in children examined at the Oral Diseases Clinic at the Department of Dermatology - University of São Paulo - Brazil. Cases were retrospectively studied from the hospital records from 2003 to 2015. A hundredsix children have been examined. Commoner lesions examined included mucoceles and aphthae. Rare and difficult cases were also seen and have been published; this clinic is based in a tertiary hospital center that deals mostly with complex cases.