We report a case of desmoid tumor in the submandibular region in an 18-month-old girl. Head and neck desmoid tumors are uncommon in children and diagnosis is a difficult task because the tumors are often classified as different types of fibromatosis. This histologically benign affection is characterized by local expansion or destruction and tends to recur. Pathology gives the positive diagnosis, showing fibroblastic monoclonal proliferation between the cellular center and the collagen periphery. Electron microscopy evidences an abundant collagen network enclosing a polymorphous cellular proliferation. Immunohistochemistry defines vimentin and actin positive desmoid tumors. Surgery is usually the therapeutic choice. Chemotherapy and radiotherapy may be used in conjunction with surgery in situations of recurrence or unsatisfactory surgical margin. There is a risk of recurrence which can be detected with regular follow-up examinations.