Objective: To report a case of carcinoma ex pleomorphic adenoma on a young patient. Introduction: Carcinoma ex pleomorphic adenoma typically presents in patients in the sixth decade of life, with a history of parotid tumor of long standing. Alarm symptoms are present in 50% of cases and survival is mainly correlated with the degree of differentiation and tumor invasion. Case report: A 33 years old woman with right parotid tumor of five years of evolution with slow growing and no symptoms. During the last year, present accelerated growth and stabbing pain. Total parotidectomy was performed without complications or sequelae. The biopsy confirms carcinoma ex pleomorphic adenoma. Discussion: The long-standing pleomorphic adenoma may present malignant transformation in up to 12%. We discuss risk factors, clinical presentation and diagnosis of carcinoma ex pleomorphic adenoma.