[en] Objective: To investigate the biological properties of ¹⁵³Sm-N-(2-hydroxyethyl) ethylene diamine-1, 1, 2-tri (methylene phosphonic acid, HEDTMP), a new kind of bone seeking compound; and to see if this radiopharmaceutical could be explored for target therapy of bone metastases. Methods: With ⁹⁹Tc^m-methylene diphosphonate (MDP) and ¹⁵³Sm-ethylene diamine tetramethylene phosphonic acid (EDTMP) being used as control agents, respectively, the plane bone scanning on New Zealand rabbits and Wistar rats and the biodistribution experiment of ¹⁵³Sm-HEDTMP on Kunming mice were performed. Results: 1) The plane bone scanning on rabbits and rats showed that ¹⁵³Sm-HEDTMP was principally absorbed by skeletal system. Skull, spine and leg bones could be observed as clearly as the images by ⁹⁹Tc^m-MDP and ¹⁵³Sm-EDTMP. 2) Mice trial also indicated the high bone seeking of ¹⁵³Sm-HEDTMP. The skeletal uptake was 19.13, 24.54 and 18.95% ID/g at 30 min, 3 and 24 h, respectively, after the injection. Kidney seemed to be the major excretory organ. The clearance from blood was quick and the retaining amount in non-target organs was small. 3) The bone uptake and target to non-target ratio of ¹⁵³Sm-HEDTMP were higher than that of ¹⁵³Sm-EDTMP. Conclusion: ¹⁵³Sm-HEDTMP showed its fine biological properties which could be compared favorably with the commonly used bone radioactive agents, and it is well worth further research as a promising potential radiopharmaceutical in nuclide treatment for bone metastases