1. Thirty one fractures of the shaft of the tibia were treated by Küntscher intramedullary nailing (closed 26 cases) from Dec. 1979 to Oct. 1985. 2. The fractures were classified into extension type(62%) and flexion type(38%). 3. The straingt nail with bent proximally was used for the extension fractures and the nail with a curve near of each end for the flexion type. 4. In the most cases of simple fracture, we used Küntscher nail of 12mm diameter.interlocking were used in addition to a Küntscher nail(static 13 cases, dynamic 8 cases). In the case of interlocking, nail should be at least 13mm in diameter. 5. The nail was inserted just above or superolateral to the tibial tubercle. 6. The bony union was demonstrated radiographically at 14.4 weeks, and hopitalization period was less than 2 weeks in twelve cases and 3 weeks in the three cases. 7. The major complication were delayed union(1 case) and infection(2 cases).Posterior angulatory deformity greater than 5° appeared in two cases. 8. The cross leg pedicle graft combined with Küntscher nailing would be preferable procedure in the case of open fracture with skin defect.