A method is described for labeling autologous leukocytes with indium-111 oxine, which is used for localizing inflammatory processes. To an aqueous solution of indium-111 chloride was added sodium acetate buffer, pH 5.0, and then a freshly prepared solution of oxine (8-hydroxyquinoline) in ethanol. After 3-5 minutes of incubation at room temperature, the chelated indium-111 oxine was extracted with chloroform, evaporated to dryness, redissolved in ethanol, and diluted with 0.9% saline. Leukocytes were isolated from venous blood by centrifugation at 300-350 g and resuspended in 0.9% saline. The cells were labeled by adding the indium-111 oxine solution to the leukocyte suspension. Clinical results have shown indium-111-labeled leukocytes to be highly specific for abscess localization. Indium-111 is useful for imaging because its gamma emissions are suitable for external detection and its half-life of 67 hours allows studies to be performed over several days without presenting an excessive radiation dose to the patient.