In order to obtain union and lengthening in the tibial defects of adult rabbits; comparison-distraction and bone transport methods were performed by using external fixator. Clinical, histological and radiological evaluation of the results were done. Sufficient union was observed in all rabbits trea/ed with compression-distraction method. While the union in the proximal site of the defect in rabbits treated with transport method was sufficient, the union in the distal site was not sufficient.