Granulocytic (CFUC) and erythroid (BFUE) progenitor cells have been rapidly purified from human peripheral blood approximately 140 fold by combining centrifugation on a density cushion and immunoadherence cell separation methods. An initial light density (d less than 1.071 g/cm3) mononuclear cell fraction, enriched for progenitor cells, was obtained by centrifugation of whole blood on a modified Ficoll-Hypaque density cushion. Cultures of the light-density cells gave cloning efficiencies (defined as the percentage of total cells plated) of 0.008% and 0.015% for CFUC and BFUE respectively. Further purification was achieved by negative selection whereby selective populations of immunocompetent cells were removed. Thus, B cells and monocytes (as well as up to 50% high affinity Fc receptor bearing cells) were simultaneously depleted by immunoadherence to plastic petri dishes coated with rabbit anti-human IgG. Leu-3a positive (helper) and Leu-2a positive (suppressor) T cells were then simultaneously depleted by an indirect "panning" method, whereby the T cell subsets were coated with the corresponding murine monoclonal antibodies prior to their removal by immunoadherence to plastic petri dishes coated with goat anti-mouse IgG. The final cell fraction, which contained approximately 2% of the initial light density cells were highly enriched for CFUC and BFUE, having cloning efficiencies of 0.37% (+/- 0.30) and 0.27% (+/- 0.24) respectively. Overall, the purification procedure used in the present study is relatively rapid, simple and reproducible. As such, it should provide a viable and convenient alternative approach to previously published methods for purifying hematopoietic progenitor cells from human peripheral blood.