In a group of fifty possible myxomata of the soft tissues of the extremities, sixteen were considered histopathologically to fulfill Stout's criteria for the diagnosis of myxoma. Fifteen of the sixteen fell into one of two groups. The main distinguishing features of the two were the arrangement of the silver-staining fibers and the vascular pattern. Tentative inistopathological groupirng into myxoma and myxosarcoma was made by utilizing these features. Correlation of the clinical course with the two histopathological groupings justified the histopathological diagnoses. Tumors which histopathologically were myxomata were cliruically benign; those which histopathologically were myxosarcomata were capable of metastasizing. Local excision of myxomata appeared to be adequate treatment. Experience in this small series suggested, however, that in cases of myxosarcoma more radical excision and even primary amputation, after biopsy, is justified by the clinical course of this lesion. It seems likely, therefore, that the growth potentialities of myxomata and nnyxosarcomata can be foretold, and that clinical prognosis can be given on the basis of histopathological examination,