This work reviews influence of patient age on tactics of limb lengthening, prognosis of scientifically grounded amount of tibial lengthening. The mentioned data are based on treatment experience of 102 patients with achondroplasia aged from 6 to 30 years, who were treated at the RISC “RTO” in 2000-2009. All of them underwent bilocal tibial lengthening (204). The received anthropometric and radiographic measurement allowed us to study growth rate of tibia and fibula on X-rays from the age of 1 year to 30 years.