Autologous stem cell transplantation is an important part of therapy in patients with multiple myeloma. Some patients fail to collect the desired number of stem cells while others require multiple apheresis to reach the desired apheresis target. The aim of this study was to determine the predictive factors and if the hematopoietic kinetics of recovery were predictive for outcome of stem cell mobilization in cyclophosphamide + growth factor (CY-GF) mobilized patients. Three hundred and ninety six consecutive CY-GF mobilization attempts between January 2000 and December 2009 at Mayo Clinic, Rochester, MN were analyzed. Patients were divided into three groups: optimal (>5 x 106 CD34/kg), suboptimal (25 x 106 CD34/kg) and poor (<2 x 106/kg CD34+ cells) mobilization groups. About 86% of patients had optimal stem cell collection, whereas 8% had suboptimal collection and 6% had poor (or failed) collections. Age, Hb, WBC, and platelet levels had an impact on mobilization results. Time to peripheral blood (PB) CD34+cells >10/mu L predicted for efficiency of collection and the interval between recovery of WBC>1 post-CY to PB CD34+ cells>10 was shorter in the optimal collection groups. These findings suggest that for patients with a PB CD34+ cell count below 10/mu L on Day 13 following CY or 1 day after the WBC>1 x 109/L, addition of plerixafor may be helpful to salvage the mobilization attempt. Am. J. Hematol., 2012. (C) 2011 Wiley Periodicals, Inc.