The preparation of ¹⁶⁶Ho labeled hydroxy apatite (HA) particles for radiosynovectomy applications is described in this paper.¹⁶⁶Ho was prepared by the irradiation of Ho₂O₃ at a flux of 1.8 x 10¹³ neutrons/cm²/s for about 7 days. The irradiation resulted in the production of_˜17 GBq of ¹⁶⁶Ho activity at the end of six hours post end of bombardment and the corresponding specific activity was_¨ 3 – 4 GBq/mg of Ho. The irradiated target was dissolved in 0.1 N HCl solution. Radionuclidic purity was ascertained by high resolution gamma ray spectrometry. HA particles were synthesized and characterized by X-ray diffractometry. Labeling studies were carried out with and without citric acid as a transchelating agent. Radiochemical yield and purity of the ¹⁶⁶ Ho-HA particles were ascertained by paper chromatography and by paper electrophoresis techniques. Labeling yield of > 98% could be achieved at pH7, with 40mg of HA particles and 8.6μg of Ho.¹⁶⁶ Ho-HA particles prepared were stable for 72h. Bio-evaluation of the ¹⁶⁶ Ho- HA particles were carried out by injecting _˜74 MBq dose in 200 μL(_˜8mg of ¹⁶⁶ Ho-HA particles) directly into the arthritis induced knee joints as well as into the healthy knee joints of white New Zealand rabbits. Images of the injected joints of the animals recorded using a gamma camera at regular intervals showed good retention.Blood samples were collected from the animals and activity assayed in a scintillation detector. Experiments were also carried out under identical conditions in normal rabbits. In both the cases, it was observed that there was no significant extra articular leakage of the injected activity over the study period of 96 h post injection.