In connection with the uptake of 67Ga into the inflammatory tissues, such as granuloma tissues produced with turpentine oil, the influence of Fe3+ on the uptake of 67Ga into mouse granuloma and normal tissues and on the uptake of 125I-labeled transferrin and 59Fe were investigated. Fe3+ decreased the uptake of 67Ga into the liver and spleen, but had no influence on the uptake of 67Ga into the granuloma tissues. The uptake patterns of 125I-labeled transferrin and 59Fe in the granuloma tissues were not consistent with that of 67Ga at all. These results show that the uptake of 67Ga into the granuloma tissues occurs in a free, transferrin-unbound form, but into the liver and spleen in a transferrin-bound form.