(198)Au sodium thiomalate was administered intramuscularly to two groups of mature rabbits. One group was pretreated intramuscularly with non radioactive gold prior to injection of (198)Au sodium thiomalate. The other group recieved no pretreatment. 1) Serum radioactive gold level reached a peak at 3 hours after injection. Serum radioactive gold level decreased more rapidly in the pretreated group than in the non-treated group. 2) Serum gold concentration was higher in the pretreated group than in the non-treated group. 3) Urinary excretion of radioactive gold was more rapid in the pretreated group than in the non-treated group. 4) In peripheral blood of both groups, the radioactive gold level was in the descending order of serum, plasma and whole blood. 5) The effective half life of radioactive gold in the pretreated group was 2.51 days in serum, 2.50 days in whole blood and 2.16 days in plasma. From this finding and (4), gold salt probably did not combined with fibrinogen. 6) Radioactive gold level in feces in both groups reached a plateau at 48 hours and gradually decreased at 96 hours. 7) Gold salt distribution was detected in the descending order of renal cortex, renal medulla, spleen, lymphonode and liver. 8) Histologically, gold salt was detected in epithelial cells of the urinary tubules, in kupffer's cells and around the lymphoid follicles. 9) By zone electrophoresis, 50.6% of radioactive gold on 100% of non-radioactive gold was combined with albumin fraction. By paperchromatography, 79.1% of radioactive gold was combined with albumin fraction. 10) Gold salt did not attach to red cell surfaces.