PURPOSE : Under the principle of rigid fixation and bone graft, we analyzed and compared the clinical results in the treatment of nonunion of long bone fractures using plate fixation and intramedullary nailing with or without bone graft. MATERIALS AND METHODS : We used 19 cases of plate fixation and 19cases of intramedullary nailing with or without bone graft for the treatment of the nonunion of long bone from Mar. 1994 through Feb. 1997. We analyzed and compared the clinical results of plate fixation and intramedullary nailing with bone graft in the treatment of nonunion of fracture. RESULTS : The mean bone union time according to nonunion type in case of plate fixation was 22.6 weeks in the hypertrophic type and 16.4 weeks in the atropic type(p<0.005). In case of intramedullary nailing was 20.4 weeks in the hypertrophic type and 15.3 weeks in the atropic type(p<0.05). According to the bone graft in case of plate fixation, 20.8 weeks in the autogenous bone graft and 19.3 weeks in the combination of autogenous bone graft and allo-bone graft(p>0.05). In case of intramedullary nailing, 16.9 weeks in the autogenous bone graft and 22.7 weeks that dosen't bone graft. According to the radioligical bone union time was 20.1 weeks in the plate fixation and 18.7 weeks in the intramedullary nailing(p>0.05). CONCLUSION : There was on significant difference according to the method of fixation, but the treatment of nonunion of long bone in lower extremities using intramedullary nailing will be good because of early ROM exercise and weight bearing ambulation than plate fixation. Although the type of nonunion is hypertrophic in the case of intramedullary nailing, bone graft is helpful to promote bony union.