The influence of preoperative irradiation on surgical complications in 42 patients with Ewing's sarcoma was analysed. After preoperative irradiation and chemotherapy, 35 of 40 patients showed a good histological response and 25 of 40 patients had no viable tumour cells in the resected specimen. Local relapse alone did not develop, local relapse and metastasis developed in 2 patients and metastasis alone in 15 patients. Surgical complications appeared in 12 of 42 patients: 9 of 19 central tumours (19 pelvic lesions), 1 of 13 proximal and 2 of 10 distal tumours. Surgical complications after preoperative irradiation are distributed as follows: delayed wound healing 8, hematoma 2, thrombosis 2, skin infection 1, and abscess 1. On the other hand, complications appeared in 2 of 28 patients without preoperative irradiation: none in 9 patients having central tumours including 2 pelvic lesions, 1 in 12 patients with proximal tumours, and 1 in 7 patients with distal tumours. The multivariate regression test showed that the tumour site (central) is an influencing factor in the appearance of surgical complications. In central tumours, the surgical complication rate increases after preoperative irradiation; however, it is affected by the increase of the ratio of patients with pelvic tumours.