The purpose of this study is to evaluate the effectiveness of Ilizarov external fixator in the treatment of difficult tibial fractures. We analyzed 37 cases with closed or open comminuted tibial fractures and unstable segmental fractures, treated with Ilizarov external fixator between August 1993 and August 1997. Among them, 21 cases were treated with simple application of Ilizarov external fixator. A compression of the fracture site (6 cases), translation (2 cases) and internal transportation technique (2 cases) were applied, and bone graft was applied in 5 cases. We obtained bony union in all cases with Ilizarov method except one case converted to intramedullary nailing due to delayed union. The average time required for bone union were 21 weeks in closed fractures, 26.2 weeks in open fractures. The complications developed were as follows; pin irritation in 14 cases, pin tract infection in 9 cases, adjacent joint contracture in 3 cases, delayed union in 1 case and malunion in 1 case. According to Tuckers classification, the results were graded as excellent in 18 cases, good in 14 cases, fair in 3 cases, poor in 2 cases. In conclusion, Ilizarov external fixation is one of the useful treatment option in closed or open comminuted tibial fractures and unstable segmental fractures.