Abstract: A basal serum-free medium and a hematopoietic cell growth and differentiation-promoting serum-free medium based thereon are provided for the maintenance, cultivation, growth and differentiation of erythroid progenitor cells, other hematopoietic progenitor cells, and leukemia cells in which the effects of various growth factor compounds can be quantitatively evaluated. Both media are wholly serum-free and contain no intrinsic growth factor compounds. The hematopoietic growth and differentiation medium consists essentially of the basal serum-free medium to which has been added at least one primarily but not exclusively growth-promoting agent selected from heme or hemin, interleukin-3 and recombinant human stem cell factor (and optimally all of them), and at least one primarily but not exclusively cell differentiation -promoting agent selected from erythropoietin (Epo), insulin-like growth factor (IGF) and a retinoid (and optimally including all of them).