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Context: Limb lengthening demands constant monitoring of the regenerate bone by frequent radiological examinations. Aims: The aim of the study was to explore if sonography can be used in place of radiography for monitoring distraction osteogenesis. Settings and Design: This study was a prospective and observational study. Subjects and Methods: Thirty-five consecutive patients with a mean age of 24, where tibia was monofocally lengthened by mean of 5.5 cm ± 0.5 cm were included in the study. Along with all radiological assessments (every 2 weeks during Distraction Phase [DP] and 4 weeks during Maturation Phase [MP]), concurrent sonographic assessment was done and findings compared. Statistical Analysis Used: Descriptive methods. Results: Reparative granulation tissue in the distraction gap and endosteal reaction at both ends were visualized sonographically at 2 weeks before any radiological evidence of regeneration. The echolucent gap increased as distraction progressed with the internal hyperechoic signals getting organized to linear structures at 4 weeks when first radiological evidence was noted. This echopositive portion of the regenerate bone narrowed down by 6−8 weeks when radiographs showed bony trabeculae, more so in MP. By 14−16 weeks of MP, there was a significant reduction of echopositive zone, where more of regenerate got converted to hyperechogenic cortical bone. Sonography was poor in measuring distraction gap and assessing mechanical axis alignment. Sonographic findings correlated well with the findings of accelerated and poor regeneration on radiographs during DP and aided modification of distraction. Conclusions: Sonography is a valuable tool in DP and first half of MP and many radiographic examinations during these phases may be replaced by sonography. Judicious and combined application of sonography and radiography must be explored for superior characterization and monitoring during limb lengthening, with lesser radiation exposure.