BACKGROUND Clear cell sarcoma, or malignant melanoma of soft parts, is a rare tumor that occurs predominantly in the extremities of young adults. The importance of surgery has been well established. However, the role of adjuvant radiotherapy has yet to be determined. METHODS Thirty cases of clear cell sarcoma that occurred in The Netherlands between 1978 and 1992 were studied retrospectively. Follow‐up information on 29 patients was obtained; the follow‐up period ranged from 4 to 241 months, with a median of 30 months. All tumors occurred in the extremities, mostly of young adults. RESULTS The 5‐year survival rate of the 29 patients was 54%. For the 23 patients who presented with localized disease, the 5‐year survival and 5‐year disease free survival were 65%. Eleven of these patients remained disease free after resection of the primary tumor. Patients with a tumor 2 cm or smaller had better survival than patients with a larger but still‐localized tumor (P = 0.009). Adjuvant radiotherapy to the primary tumor site also seemed to have a beneficial effect on survival (P = 0.036). All patients with a local recurrence (8 patients) or regional lymph node metastasis (13 patients) developed distant metastasis. Fourteen of 18 patients with distant spread died of their disease; 2 patients were still alive with disease and 2 patients were disease free, 7 and 32 months after resection of solitary distant metastases. CONCLUSIONS Early diagnosis and initial radical surgery are essential for a favorable outcome. Once regional lymph node metastasis or hematogenous dissemination has occurred, the prognosis is dismal. Cancer 1999;86:969–75. © 1999 American Cancer Society. Early diagnosis and control by radical surgery after exploration of the regional lymph nodes is essential in the treatment of patients with clear cell sarcoma. Adjuvant radiotherapy may have a favorable influence on the final outcome.