[en] Samarium-153 has suitable physical properties for metastatic bone cancer pain palliation with 46.7 hr half-life. Not only decays it with multi-energetic B-radiation but also emits a gamma-ray at 103 keV which is suitable for imaging during therapy. The optimization of ¹⁵³ Sm production, by irradiation ¹⁵² Sm₂ O₃ as a solid and liquid target, is conducted in TRIGA Mark III research reactor. The feasibility to label it with EDTMP, a bone seeking agent, is also studied. The specific activity obtained from liquid target is about 2 times higher than solid target. At least 500 mCi/week can be produced with specific activity about 50 to 70 mCi/mg Sm. EDTMP as Na-EDTMP and Ca-EDTMP is labelled with ¹⁵³ Sm at various conditions. The radiochemical purity achieved, is greater than 99% (85 mCi of ¹⁵³ Sm labelled with Na-EDTMP or Ca-EDTMP, molar ratio of Sm:EDTMP 1:10 and 1:100 respectively, pH 7.5-8). The biodistribution in animals of ¹⁵³ Sm-Na-EDTMP showed similar results as obtained from ¹⁵³ Sm-Ca-EDTMP but slightly higher uptake in various organs and showed high skeletal uptake up to 32% at 24 hr post injection. The labeled compound obviously undergoes rapid removal, completely clearance into urine within 24 hr. This labeled compound is under clinical trials