We retrospectively examined whether adjusting the amount of apheresis using the number of CD34-positive cells in the product during peripheral blood stem cell collection (PBSCH) led to optimal collection. A total of 52 subjects, including 28 allogeneic and 24 autologous PBSCH, were analyzed. We observed a correlation between the number of CD34-positive cells in the product during PBSCH (mid-apheresis) and after PBSCH (final product): total (R = 0.986), allogeneic (R = 0.973), autologous (R = 0.996).