PB HPC quantification is very useful to quickly determine the initiation of PBPC apheresis especially for patients with higher concentrations. For patients exhibiting a lower HPC count (<5 x 10(6)/L), other parameters such as a CD34 test may be needed. Such a policy associated with a length of apheresis adapted to the richness in the PB CD34+ cells allows for optimizing the organization of centers with an improvement in patient comfort and economical savings.