The clinical course and morphologic (light and ultrastructural) characteristics of a case of verrucous carcinoma of the lower gingival mucosa are presented. Clinical course of the patient was unfavorable following surgery (supposedly incomplete) and radiotherapy (6,000 R) of the tumor. The therapeutic factors that may influence an unfavourable prognosis are commented upon, especially in regard to a slow-growing neoplasm with a generally good course.