PURPOSE : This study was to evaluate the results and complications in gap nonunions of the tibia treated by Ilizarov method MATERIALS and METHODS : We reviewed 30 patients of tibial nonunions(23 atrophic, 7 hypertrophic) with bone loss(1-l3cm, mean 4.6cm) who were treated by Ilizarov technique. The causes of bone defect were open fracture with bone loss(15 cases) and infected nonunions(15 cases). Bone defects were closed by Ilizarov bone transport technique. RESULTS: All patients had satisfactory union. The mean distraction-consolidation index (distraction-consolidation time/ distraction gap) was 1.3 months/cm. The younger patients and metaphyseal lengthening healed faster than the older patients and diaphyseal lengthening. Even though, we met with the numerous complicationt such as pain around the pin site, pin site infection and delayed union, we could successfully treat most of them. CONCLUSION : The application of Ilizarov techniques to nonunions of the tibia with bone defect was very effective, but correct technique and careful follow-up examination was required to avoid complications.