Abstract: An in vitro method for functional assessment of haematopoietic progenitors which makes it possible to assess the ability of haematopoietic progenitor cells (HPCs) to respond to growth factors and proliferate in products used for HPC transplantation, without need for cell culture. The disclosed method can be used for functional quantification of haematopoietic progenitors pre-transplantation and can also be used as a functional assay or functional prognostic biomarker for leukaemia or other tumours. The method could be used to separate HPCs from cell mixtures and collect them for use in cell therapy.