Abscess-induced animals and normal animals were treated with 67Ga-citrate. Abscess, kidney, heart, lung, and spleen were excised and homogenized. After removal of the nuclear fraction, each of these homogenates was digested with protease. After digestion, the supernatants of the reaction mixtures were applied to a Sephadex G-100 column. Resultant eluates were analyzed for radioactivity, protein, uronic acids, and sialic acids. Sodium sulfate-35S was administered to animals that were then treated by the same procedure as that followed for animals treated with 67Ga-citrate. In abscess, kidney, lung, heart, and spleen, sizeable amounts of 67Ga had been bound to the sulfated acid mucopolysaccharides with molecular weights of about 10,000, and to the sulfated acid mucopolysaccharides, a species whose molecular weights exceeded 40,000. Based on the results presented here, it is clear that 67Ga-binding substances in abscess and also in the above four organs are sulfated acid mucopolysaccharides.