Forty-four cases of lymphangiosarcoma treated at Memorial Sloan-Kettering Cancer Center were reviewed. With the exception of four patients with primary lymphangiosarcoma of the scalp, all patients had had chronic lymphedema of the involved limb for many years, usually following mastectomy for breast carcinoma, but occasionally due to other cases. Although chronic lymphedema could be implicated in the etiology of lymphangiosarcoma in all patients with neoplasms of an extremity, a significant number of patients did not have a history of radiation therapy at the site where their tumor developed. Histologically, although there were no differences in the lymphangiosarcomas between any of the groups of patients, the morphology of the tumors was influenced in the individual patient by the size and anatomic site of the sarcoma. Early amputation seemed to give the best chance of long-term survival, with responses to wide resection, chemotherapy, and radiation therapy generally only of short duration. Amputation after local recurrence was ineffective in preventing pulmonary metastases and death. At present, early amputation appears to be the treatment of choice for patients with lymphangiosarcoma.