The radiographs of 57 patients who had undergone 58 callus distractions and 13 epiphyseal distractions were evaluated. During the course of treatment, the density of the distraction areas on radiographs was measured in total and along the medial, lateral, ventral, and dorsal margins using a digital radiograph processing system. The densities of the whole distraction length were correlated to the following parameters: age of patient, start of distraction after corticotomy, mean distraction speed, mean amount of weight load during the period of distraction and consolidation, location of corticotomy (distal femoral metaphysis versus the proximal tibial one), and diclofenac medication. Except for the location of corticotomy and the diclofenac medication, the density was influenced by all these parameters. Age of the patient and weight load were the most important parameters. Patients with leg shortening caused by poliomyelitis and a patient with a shortened leg after amniotic strangulation showed a slower rise of the density trend curve on radiographs than the other patients. When comparing the different regional density curves, a significant gradual density decrease could be observed from the medial to the lateral side in the femur, from lateral to medial in the tibia, and from the dorsal to the ventral side in both bones. The respective differences between lateral and medial density, and between dorsal and ventral density, were significantly higher in cases of callus distraction than in cases in which epiphyseal distraction had been used. The amount of bone regeneration varied regionally primarily because of the inhomogeneous soft tissue covering of the bone and the impairment of its local blood supply by the surgical exposure for the corticotomy. The clinical relevancy of the various parameters for osteoneogenesis is discussed in this article.