In the period from January 1990 to the end of December 1995 intramedullary nailing was performed in 294 patients with 156 fractures of the femur and 162 fractures of the tibia. Early nailing within the first 24 h after trauma was realized in 70% of the femur and in 64% of the tibia fractures. A synopsis focusing on local complications after intramedullary nailing is given on the basis of our results and a thorough analysis of the literature. Iatrogenic fractures of the femoral neck (0-5%), of the proximal femur (0.8-11.2%) and of the tibial head (0-8.3%) represent important intraoperative complications. Less frequent, but even more serious, are intraoperative lesions of nerves and arteries, as well as the development of compartmental syndromes of the lower leg (0-8.6%). Lengthy procedures and the use of traction tables seem to foster those complications. After primary intramedullary nailing, non-unions of the femur can be expected in 1-2% and of the tibia in 2-4%. The corresponding rates of osteomyelitis are 1-1.5% and 2-3%, respectively. After secondary nailing, particularly when changing from external fixation, and in cases of open fractures, the risk of deep infection is essentially elevated. Intramedullary nailing of the femur presents an important tendency to external torsional malalignment. In our investigation the torsional tolerance of 15 degrees was exceeded in 26%. A corresponding postoperative shortening of more than 2 cm length difference can be expected in 1.7-9.8%. Spiral fractures of the distal tibia offer a critical tendency to secondary varus and torsional malalignment, particularly after unreamed nailing and consecutive shortening due to breakage of locking bolts. The therapeutic indications of fracture stabilization in cases of unstable metaphyseal fractures should be reviewed.