Contact mucositis is an inflammatory mucosal reaction caused by many agents. A case of a 53-year-old man with contact-type allergy in oral mucosa due to cinnamon chewing gum is presented. This condition should be considered in the differential diagnosis of nonspecific oral lesions. Parole chiave: allergic reaction, cinnamic aldehyde, cinnamon, hypersensitivity, oral mucosa, oral mucositis