OBJECTIVES: A disintegrin and metalloproteinase (ADAM)-10 is expressed in rheumatoid arthritis (RA). In this study, we focused on ADAM-10 as a predictive factor for the treatment with biologics in RA. METHODS: The levels of ADAM-10 and fractalkine/CX3CL1 in RA and healthy controls serum were measured using enzyme-linked immunosorbent assays. Fifteen patients were treated with adalimumab (ADA), and 20 patients were treated with tocilizumab (TCZ). RESULTS: ADAM-10 positively correlated with fractalkine/CX3CL1 in the sera of RA patients and was presented at a significantly higher level compared to that in normal serum (487 ± 80 pg/ml and 85 ± 33 pg/ml, respectively, p < 0.05). ADAM-10 highly correlates with fractalkine/CX3CL1 in the sera of RA patients. The level of ADAM-10 decreased after the treatment with TCZ but not with ADA. In addition, we found that the level of ADAM-10 in TCZ responders was significantly higher than that of the TCZ nonresponders at 24 weeks (619 ± 134 pg/ml and 109 ± 25 pg/ml, respectively). Multiple regression analysis showed that ADAM-10 was only identified as independent predictive variable for the improvement of DAS28 (ESR) at 24 weeks. CONCLUSIONS: ADAM-10 may be a predictor of the effectiveness of TCZ in treating RA.