Approximately 60% of the 65Zn in labeled homogenates of rat intestinal mucosa was recovered in a 45,000g supernatant, and about 50% of the counts in this supernatant could be recovered in a 45-80% ammonium sulfate precipitate. The bound 65Zn in the ammonium sulfate precipitate could be resolved into two peaks by gel filtration on Sephadex G-100. The first radioactive fraction consisted of substances having molecular weights of 150,000 or more, and the second tion consisted of substances having molecular weights in the range of 10 to 15,000. Electrophoresis of the material from the first Sephadex peak always yielded 10 or more visible protein bands; whereas material from the second peak yielded either 3 or 4 visible bands. It was not possible to determine which, if any, of the protein bands were originally labeled, as the 65Zn dissociated during electrophoresis and migrated to the cathode. To date, there is no evidence to link any of these compounds with intestinal absorption of zinc.