In a laboratory model granulocyte concentrates are produced by a procedure of gravitational leukopheresis. Hydroxyaethyl starch (HAS) served as an accelerator of sedimentation. In a parallel test arrangement a preparation of hydroxyaethyl taken from the industrial production of the GDR and a control preparation (Plasmasteril) was used. The regaining rate of this method amounts to about 70 per cent with 98 per cent of living cells in the concentrates. Vitality, performance of phagocytosis and ability of migration will only reduce to a slight degree during the first 4 hours, after that time, however, they will decrease significantly. There are no essential differences between the results of both preparations.