After the completion of combination therapy designed to achieve local control of Ewing's sarcoma, 13 patients with either truncal primary lesions or proven metastases were given 150 rad of total body irradiation over 5 weeks followed by cyclophosphamide, doxorubicin, imidazole carboxamide, and vincristine. 11 patients received autologous cryopreserved marrow infusions. In 2 patients marrow collections were not attempted. Two patterns of haemopoietic recovery were observed: 8 patients, who had received marrow infusions, showed leucocyte, granulocyte, and platelet recovery by 27, 28, and 30 days. 5 patients, 3 of whom had also received marrow, showed more delayed recovery with leucocyt, granulocyte, and platelet recovery at 45, 53, and 77+ days. Delayed recovery in patients receiving marrow seemed to correlate with aberrations in marrow freezing-rate during phase change, and these aberrations could be shown to diminish post-freeze recovery of marrow granulocyte-monocyte precursor cells.