Abstract:[Objective] To explore the factors related to the outcomes of radial extracorporeal shock wave (rESW) for long bone non- union. [Methods] From September 2014 to June 2019, 54 patients received rESW therapy for long bone nonunion, involving 13 femurs, 22 tibias, 2 fibulas, 6 humerus, 7 radius, and 4 ulnas. The rESW was applied once a week for 30 minutes without anesthesia for 4 weeks. All patients were followed for at least 12 months to assess outcomes by using clinical and radiographic fracture healing criteria and VAS scores. Univariate comparison and binary multi-factor logistic regression were conducted to search the factors related to treatment outcome. [Results] Fracture healing achieved in 35 patients (64.81%) at 3 months after treatment, 39 cases (72.22%) at 6 months and 40 cases (74.07%) at 12 months after treatment. Regarding to univariate comparison, the union group had significantly higher ratio of hypertrophic bone non- union than the nonunion group (P<0.05) , whereas, the union group was significantly less than the nonunion group in terms of interval be- tween fracture and rESW treatment, the number of previous surgical operations, fracture gap and the number of rESW treatment cycles (P< 0.05). As results of logistic regression, interval between fracture and rESW treatment (OR=1.080, P=0.036) , the number of previous opera- tion (OR=4.900, P=0.015) , fracture gap (OR=1.418, P=0.010) , the type of nonunion (OR=31.054, P<0.001) and the number of rESW treat- ment cycle (OR=2.401, P<0.001) were significantly related to the outcomes of rESW therapy. [Conclusion] The rESW is safe and effective in the treatment of long bone nonunion, and its outcomes is related to the type of nonunion, interval between fracture and rESW treatment, the number of previous surgery, fracture gap. In addition, rESW therapy greater than 8 cycles might be meaningless.