we separated platelets from whole blood and incorporated them into in-ill and te-99m agents. sn-gha, tropolone, oxine (sulphate) and hmpao were used to diffuse radionuclides into the platelets. the effects of time, temperature, ph of incubation media; volume and concentration of ionophore; and volume and activity of ln-l 13m c13 and te-99m on labeling efficiency were studied.