Autologous stem cell transplant (ASCT) requires the collection of hematopoietic progenitor cells, commonly by apheresis (HPC-A). These CD34+ cells can be mobilized using Granulocyte Colony Stimulating Factor (G-CSF) only or chemomobilization plus G-CSF. Both methods may additionally include Plerixafor. The emergence of COVID-19 led to recommendations for preferential G-CSF only mobilization. To assess the impact of this recommendation on HPC-A harvesting, we analyzed data from the NHS Blood and Transplant Stem Cell Collection Registry for 1342 patients undergoing 2431 HPC-A procedures between 01/01/2019 and 31/12/2021. We compared G-CSF only, cyclophosphamide plus G-CSF (Cyclo-G) and G-CSF plus alternative chemotherapy (Chemo+G) mobilization. The outcomes collected were pre-apheresis CD34+ count, CD34+ yield per procedure, total CD34+ yield, number of apheresis procedures required to achieve the CD34+ target, mobilization failure, and Plerixafor use (+P). In multiple myeloma (MM), Cyclo-G (+/-P) mobilization produced significantly higher CD34+ yields than G-CSF only (7.44 vs. 4.75 × 10