A method for isolation and labelling of purified granulocytes with 111In-oxine for scintigraphy of inflammatory processes is described. The procedure, on average, yielded 27.6% of the initial granulocytes in the sample with minimal lymphocyte and platelet contamination. The mean erythrocyte/granulocyte ratio was 0.95. In 20 experiments, 85.3% of the total radioactivity was attached to granulocytes, 8.7% to erythrocytes and 5.9% was in the plasma. The sensitivity and the specificity for the detection of acute inflammatory processes in 44 patients were 91.3% and 81.8%, respectively.