Nine cases of fibromatosis occurring in or near the oral cavity are presented here. They are classified as nodular fasciitis (3 cases), aggressive infantile fibromatosis (2 cases), fibrosing myositis (1 case) and fibromatosis (1 case). Of the 5 cases of nodular fasciitis, 3 occurred from the fascia of the masticatory muscle and 2 from the submucous fascia of the palate and tongue. The aggressive infantile fibromatosis showed a prominent infiltrating growth and an alarming histologic appearance. One of the 2 cases showed a recurrence, but the postoperative course of both cases was uneventful for 13 years and 10 years, respectively. The fibrosing myositis is an unusual fibromatosis of the muscle, which arose within the tongue muscle. The lesion was benign and can be cured by conservative surgery.