A column immunoadsorption method, based on the high affinity between the protein Avidin and the vitamin Biotin has been used to obtain positive CD34+ or S313+ marrow cells selection. Cell suspensions from marrow samples of six healthy subjects were incubated either the monoclonal antibody S313 or HPCA 1 (My 10-like) and a biotinilated goat anti-mouse Immunoglobulins antiserum, passed over a column containing an Avidin coated Polyacrylamide matrix, at the flow rate of 1 ml/min. The phenotype and the clonogenic efficiency of the recovered adherent cell fraction were studied by cytofluorimetric analysis and haemopoietic progenitors short term cultures. The results obtained show a mean CD34+ and S313+ cells recovery greater than 50% with a lower stem cells enrichment. Although these data could not considered optimal for clinical application in haematologic neoplasias, these preliminary studies demonstrate the possible use of the method for autologous bone marrow transplantation.