P u r p o s e : We evaluated the result of tibial fracture with butterfly fragment treated with interlocking intramedullary nailing and union of butterfly fragment. Material and Method : The thirty tibial fractures with butterfly fragment treated with interlocking intramedullary nailing from 1994 February to 1997 January were followed up more than 12 months. They were classified by Henley’s classification based on the size of fragment and Johner and Wruhs’classification based on the comminution and accident mechanism. We evaluated the bone union of tibial fracture and butterfly fragment itself. Results : The time for bone union was B1-14.5, B2-16.2, B3-18.8 weeks and Type 1-15.2, Type II-17.1 Type III-18.3 weeks. In proximal and distal part of butterfly fragment, the time for bone union was 8.6 and 7.2 weeks in type I, 10.5 and 9.3 weeks in type II, and 11.8 and 10.2 weeks in type III. As the displacement of fragment were classified into 0-5, 5-10, and more than 대한골절학회지 제12권, 제4호, 1 9 9 9년 1 1월 The Journal of the Korean Society of Fractures Vol.12, No.4, November, 1999