The combination of cyclophosphamide and topotecan (cyclo/topo) has shown objective responses in relapsed Ewing sarcoma, but the response duration is not well documented. We reviewed characteristics and outcome of 14 patients with Ewing sarcoma, treated uniformly at a single institution and offered cyclo/topo at first relapse. Six patients (43%) had relapse at distant sites. All patients received first-line salvage therapy with cyclophosphamide 250 mg/m and topotecan 0.75 mg/m, daily for 5 days repeated every 21 days. The median number of cycles was 4 (range 1 to 10). All toxicities were manageable, the most common being transient cytopenias. There were also 4 episodes of febrile neutropenia, and 3 episodes of gross hematuria. Response was assessable in 13 patients and showed progressive disease in 6 (46%), stable disease in 4 (31%), and partial response in 3 (23%). Nine patients had local control, consisting of radical surgery in 2, radiation in 3, and a combination in 4 patients. Response, when it occurred, was maintained for a median of 8 months (range, 4 to 28 mo). Four patients (29%) are alive at 3, 7, 9, and 110 months after relapse; 1 is receiving cyclo/topo, 1 is on third-line therapy, and 2 are in second and fourth remission. The low toxicity of this combination, and the lack of sustained responses, warrant its investigation in combination with targeted or novel therapeutic agents in relapsed disease.