The goal of this trial was to assess the toxicity and potential efficacy of high-dose topotecan, melphalan and cyclophosphamide as a preparative regimen for patients with multiple myeloma undergoing autologous stem cell transplantation. Eighteen patients were treated, 8 for first remission consolidation, 4 with relapse sensitive disease, 3 primary refractory and 3 relapsed refractory. The median age was 56 (38 - 65) and the median number of prior regimens was 3 (1 - 8). Patients received cyclophosphamide 1 g/m2/d on days -6, -5, -4; melphalan 70 mg/m2 on days -3, -2 and topotecan 3.0 to 3.5 mg/m2/d on days -6 to -2. Peripheral blood stem cells were infused on day 0. Toxicity (Bearman Toxicity Criteria) was mostly limited to grade 1 - 2 mucositis and grade 1 diarrhea. There were no transplant-related deaths. The overall response rate at 3 months post transplantation was 89% with 17% CR, 2 of those in refractory patients. The overall response rate in refractory patients was 67%. With a median follow up of 12.3 months, 89% of patients are alive. The TMC regimen is well tolerated and produces high response rates. Further evaluation of TMC to fully assess response and survival is ongoing.