6559 Background: Autologous Stem Cell transplant (AutoSCT) is a vital treatment option for various hematological disorders including multiple myeloma and lymphomas. Peripheral blood mobilization of CD 34+ progenitor cells is usually achieved with the assistance of G-CSF alone or with chemotherapy. A common strategy has been to use High-dose Cyclophosphamide (4 gm/m2) with G-CSF. We have been using Intermediate dose Cyclophosphamide (Cy) (1.5gm/m2) with G-CSF for several years as our primary mobilization strategy. The goal is to attain an adequate collection while limiting the known complications of chemotherapy. Methods: Retrospective analysis of 136 consecutive patients (pts) (excluding prisoners) from Jan 2005 to Dec 2009 that received intermediate dose Cy with G-CSF was conducted. IRB approval was attained prior to analysis. We analyzed the adequacy of CD34+ collection and the need for hospitalization secondary to toxicity. Threshold of 2 x 10(6)/kg for lymphomas and 5 x 10(6)/ kg for multiple myeloma of CD 34+ Cells was set to determine adequacy of the collection. The number of cytopheresis days was also calculated. Toxicity was defined as the need for hospitalization. Results: 6 of 136 (4.4%, 95%CI ± 3) consented pts had CD34 screen inadequate for proceeding to collection. 11/130 (8.5%, 95%CI ±4) pts failed to meet the threshold. 10/130 (7.7%, 95%CI ±4) required >1 mobilization to meet the threshold. The median number of cytopheresis days was 2 (range1-6). 9 (6.7%, 95%CI ±5) pts required hospitalization for fever (1), pain (3), pulmonary embolism (1), confusion (1), dehydration (2) and fluid overload (1). None required hospitalization for neutropenic fever. Of the 130 pts whose stem cells were collected, 129 proceeded to AutoSCT, all engrafted by CIBMTR criteria. Conclusions: Intermediate-dose Cy with G-CSF is a safe and effective strategy for progenitor mobilization. We found a very low rate of complications requiring hospitalization (6.7%). Goals for collection were achieved in 87.5%. This warrants a comparative pharmacoeconomic analysis with strategies utilizing a CXCR4 antagonist, which is underway at our institution.