We studied the rate of in vivo elimination of hydroxyethyl starch (HES) given during low dose HES leukapheresis in 9 donors and the effect of this procedure on the in vitro function of granulocytes in 3 donors. HES was eliminated more rapidly than has been previously reported for standard leukapheresis. Serum HES declined to one-half of peak concentration between 1 and 2 days and to one-tenth of peak in 23 days. No HES could be detected in serum 90 days after leukapheresis. The function of the harvested granulocytes was compared to that of granulocytes collected just prior to the procedure by measuring superoxide generation, ingestion and cell motility. There was no significant difference in the function of granulocytes harvested by low dose HES leukapheresis compared to those collected by venipuncture before the procedure.