The fibromatoses are distinctive lesions best defined as a group of nonmetastasizing fibrous tumors which tend to invade locally and recur after surgical excision. They may be multiple and familial, their growth rate often decreases after an initial period of rapid growth, and they may even regress spontaneously. They may be complicated by contractures and are sometimes associated with diseases of other organs. Different types of fibromatoses are not found in the same patient, and recurrences are more frequent in the young. As fibromatoses do not metastasize, they should never be called low-grade fibrosarcomas. The fibromatoses can be subdivided into the “adult” fibromatoses, which occur predominantly but not exclusively in people older than 20 years, and the “juvenile” fibromatoses, which usually affect patients aged less than 20 years. The adult fibromatoses comprise the Dupuytren-type fibromatoses, and the desmoid fibromatoses. Dupuytren-type fibromatoses are further subclassified into palmar fibromatosis, plantar fibromatosis, knuckle pads, and Peyronie's disease. Desmoid fibromatoses are divided into extra-abdominal desmoids, abdominal wall desmoids, intra-abdominal desmoids, multiple desmoids, multiple familial desmoids, and desmoids in Gardner's syndrome. The juvenile fibromatoses include congenital fibrosarcoma-like fibromatosis, congenital generalized fibromatosis, congenital localized fibromatosis, fibromatosis colli, diffuse infantile fibromatosis, juvenile aponeurotic fibroma, fibrous hamartoma of infancy, recurring digital fibrous tumor of childhood, juvenile nasopharyngeal angiofibroma, hereditary gingival fibromatosis, and fibromatosis hyalinica multiplex juvenilis. A total of 140 fibromatoses seen at the Armed Forces Institute of Pathology, (U.S.A) the Australian Soft Tissue Tumor Registry, and the Institute of Medical and Veterinary Science, Adelaide, are classified in this way and their clinicopathological characteristics are described. Two conclusions are drawn from the study: 1. Surgery is generally the only effective way of treating the fibromatoses, but operations may sometimes cause more morbidity than the tumors. 2. Amputation of a limb is rarely justifiable in the treatment of the fibromatoses.