Despite peripheral blood making up 80% of all of hematopoietic cell transplants, there are similar rates of overall survival, disease-free survival, and transplant-related mortality when comparing marrow and peripheral blood as graft sources. Chronic graft-versus-host disease (GVHD) and cytokine release syndrome (CRS) are more significant in those who received peripheral blood, yet the standard of care hasn’t changed. Here, two doctors reflect on the debate.