Eighteen patients who had epithelioid sarcoma in the upper extremity were divided into two groups on the basis of treatment: marginal resection of the tumor or wide or radical resection of the tumor. Historical, demographic, histological, and staging data were recorded and were correlated with the type of treatment and the outcome. Marginal resection (excision through the reactive zone or pseudocapsule surrounding the tumor, with confirmation of a negative margin by a pathologist), with or without adjuvant therapy, led to a dismal outcome in patients who had been treated in this manner initially or secondarily (fifteen failures after seventeen procedures). Disease-free survival at ten years was significantly improved when wide resection (intracompartmental en bloc excision with a cuff of normal tissue of more than three centimeters) or radical resection was either the initial or the secondary treatment; success then was noted in nine of thirteen operations. Of twelve patients in whom a marginal resection had been done initially, three had had a recurrence, three had had a metastasis, and five had died, at a mean follow-up of seven years (range, twenty-seven months to sixteen years). At a mean follow-up of six years (range, two to fifteen years), only one of five patients in whom a secondary lesion had been treated with marginal resection was free of disease. Of the six patients who had been treated with wide or radical resection initially, none had died, one had had a recurrence, and one had had a metastasis, at a mean follow-up of seven years (range, twenty-two months to fourteen years).(ABSTRACT TRUNCATED AT 250 WORDS)