OBJECTIVE To characterize the effect of receptor activator of NF-kB ligand (RANKL) polyclonal antibody on T cell-mediated osteoclasogenesis. METHODS Rabbit anti-rat RANKL polyclonal IgG antibody was performed, performing recombinated mouse RANKL-induced osteoclastogenesis in different antibody doses (1microg/mL,5microg/mL and 10microg/mL), the number of TRAP positive multinuclear cells (cells/well) was calculated under microscopy. The cervical lymph nodes in rats were enriched T-cells for in vitro experiments. The T cell-mediated osteoclastogenesis was tested by co-culture assay of RAW 264.7 cells with formalin-fixed T cell or T cell supernatant, the number of TRAP positive multinuclear cells (cells/well) was calculated under microscopy. In some experiments, the concentration of sRANKL (soluble RANKL) was measured in supernatant by ELISA (pg/mL). SPSS 11.5 software package was used for statistical analysis. RESULTS Rabbit anti-rat RANKL antibody inhibited osteoclastogenesis by recombined mouse RANKL-induced, and dose-dependent; Anti-RANKL antibody inhibited T cell and culture supernatant induced osteoclastogensis, significantly different from that in the group without antibody(P<0.05), and dose-dependent; Anti-RANKL specific antibody also markedly reduced sRANKL concentration in supernatant, significantly different from that in the control group without antibody(P<0.05). CONCLUSIONS Anti-RANKL specific antibody blocks direct effect of RANKL and interferes with immune T cell-mediated bone resorption by reduction of sRANKL level.