Aluminum citrate, aluminum tricarballylate, and aluminum lactate were prepared to test their activity for insolubilization of the phosphate, both in vitro and in vivo, and for facilitating the excretion of administered radioactive strontium, in comparison with those of dihydroxyaluminum aminoacetate, which was previously reported as an effective agent for elimination of strontium. According to the results of experiments in vitro, aluminum tricarballylate and aluminum lactate have a stronger tendency to make phosphate insoluble, but aluminum citrate has almost no activity. In the case of experiment in vivo, on the contrary, aluminum citrate showed a considerable inhibition of gastrointestinal absorption of phosphate, and moreover, it showed no untoward effect on the growth of animals, while the other two salts seem to reduce their appetite. The effect of aluminum citrate on the elimination of strontium is shown in Tables I and II. By aluminum citrate treatment, 60% of administered ⁹⁰Sr was excreted in 24 hours and 70% in 6 days, compared with respective 35% and 45% in control animals.