PURPOSE: The mechanical stiffness of Korean radiolucent carbon/graphite ring fixator(KRCRF) was analyzed and compared with those of conventional stainless steel Ilizarov system and the Smith- Nephew carbon fiber circular external fixator. MATERIALS AND METHODS: The transfixing olive pins of the circular fixator on the acryl pylon were assembled in 90degrees- 90degrees and 135degrees- 45degrees configuration, respectively. And the fixator-pylon model was loaded with Instron model No. 8500 in three testing modes: axial compression, anteroposterior(AP) bending and lateral bending. RESULTS: As compared with stainless steel Ilizarov fixator, the KRCRF was significantly more stiff on the axial compression test regardless of the ring size(140 mm and 200 mm diameters) and transfixation configuration. But, it was less stiff on the anteroposterior(AP) and lateral bending tests. When compared with the Smith-Nephew carbon fiber circular external fixator, the KRCRF was generally more stiff on the axial compression, AP and lateral bending tests regardless of the ring size(140 mm and 180 mm diameters) and configuration, except the AP bending stiffness in 90degrees- 90degrees configuration and lateral bending stffness in 135degrees- 45degrees configuration on the 180 mm diameter frame. CONCLUSION: Considering the radiolucency, weight and biomechanical stffness, we think that the KRCRF is an excellent substitute for the imported circular fixators made of stainless steel or carbon/graphite.