Patients (pts) with fulminant progression (FPG) of multiple myeloma (MM) after autologous stem cell transplantation (ASCT) have poor prognosis. Pancytopenia, extramedullary disease, and/or renal impairment are often present, and treatment options are limited. We have retrospectively evaluated 31 pts with FPG of MM after ASCT who were treated upfront salvage therapy with melphalan 100 mg/m(2) (MEL 100) followed by PBSC support and consolidation therapy using regimens containing thalidomide (n = 16) or bortezomib (n = 15). The overall response rate (ORR) was 58% (18/31). After MEL 100, one patient achieved complete remission (3%), 26% of pts very good partial remission, 29% of pts partial remission, and 42% of pts stable disease. Progression within 3 months after MEL 100 occurred in 35% of pts. The median follow-up from MEL 100 was 8 months. The median TTP was 5 months (range, 2-15 months), and the median OS was 8 months (range, 3-23 months). There were no treatment-related deaths. In fulminant progression of MM, upfront MEL 100 is a safe salvage regimen with good response rate (ORR, 58%). Treatment with upfront MEL 100 followed by a thalidomide- or bortezomib-based regimen can prolong overall survival to more than 12 months in 33% of pts with fulminant progression of MM.