A rat model for the study of closed fracture healing is described. Standard closed tibial fractures were produced with specially designed pliers in 24 rats. All fractures were located in the middle third of the tibia and healed without complications as delayed union, infection or soft tissue problems. The average angle of the fracture line with the axis of the tibia on lateral view was 80 +/- 2 degrees (SEM). The model is considered to be suited for the study of closed fracture healing processes. Closed intramedullary fracture fixation, can also be evaluated in this model.