In fit patients with newly diagnosed myeloma, high-dose chemotherapy (HDCT) followed by autologous stem cell transplantation (ASCT) is considered standard of care. For mobilization of CD34+ cells for ASCT, combined cytotoxic chemotherapy and G-CSF is commonly used. However, the importance of cytostatic chemotherapy for reliable mobilization remains unclear. This prospective randomized phase II non-inferiority trial compared G-GSF only (G) compared to standard chemotherapy/G-CSF (CG) for CD34+ mobilization. The primary endpoint was a less than 15% difference in successful stem cell collection ( ≥ 5.0 × 10