The callotasis method of limb lengthening has become a safer and popular method as development of the external fixation and lengthening device. Different kinds of lengthening device have their advantage and disadvantage but we have used the Orthofix monofixator for it's cheap-er price, simplicity to application and easiness to joint exercise. We performed limb lengthening with Orthofix in 38 patients since January, 1990. The average age was 25.6years old (8yrs to 36yrs) and the most common cause of limb lengthening was leg length discrepancy due to poliomyelitis in 26 patients and followed by 6 patients of physeal injury due to infection and 2patients of physeal injury due to trauma, 1 patient of pseudarthrosis, 1 patient of cerebral palsy and 2 patients of congenital anomaly. The lengthening was performed on tibia in 32 patients and femur in 6 patients and the average length gained by callotasis was 5.3cms (1,5 cms to 12cms). As the second stage operation we did the operation for the defomity correction during the consolidation period after lineal lengthening. The associated operation were 20 Tendo Achilles lengthening, 24 triple arthrodesis, 24 supracondylar osteotomy, 3 proximal ilio tibial band release, 1 ankle fusion and 1 Jones procedure. Frequent pin tract infection, some degrees of valgus deformity on tibia and knee stiffness were noted as complications and applied bone graft and plate fixation in 5 nonunited patients.