ESWT is used in treatment of pseudoarthrosis and may be considered for callus lengthening operations. In this study, effects of ESWT on the forming callus were studied. Transverse femoral osteotomy at mid diaphysis, internally fixated with Kirschner wires were performed on 20 male, ten-week-old white Wistar rats. In the third week, animals underwent ESWT with 1500 (Group I) and 500 (Group II) shockwaves/treatment at a generating voltage of 10 kV on their right femurs; left femurs were used as controls. In the nineth week animals were sacrificed. X-Ray and computerized tomographical analyses on both femurs were done. X-Ray data showed that bone tissue of Group I displayed a higher percentage of nonunions and secondary axial displacements than Group II. Group II had a higher percentage of unions and fewer secondary axial displacements than Group I. The radiological scores for 500-sw/treatment group were 67% of the controls. CT data showed that ESW treated right legs in both groups had a greater callus area, and lower average density of image pixel than controls. In agreement with other studies done on healing bone, no significant correlation between callus area and the level of bone healing was found.