The Authors summarize the chief phases of the development of the foot in embryonic, fetal and post-natal periods. In particular they emphasize the following concepts: 1) the foot develops in all embryonic period in 90° equinus and, at the close, adducted and markedly supinated; only at beginning of fourth mounth the foot pronates and reaches a position of midsupination and slight talus; 2) the calcaneus is initially located laterally to the talus; rapid changes occur in embryo of 27 mm: the sustentaculum tali appears and the calcaneus passes nearly entirely under the talus ("sub-talar migration of the calcaneus"); 3) tibia and fibula, and corresponding skeletal elements of the foot, present asyncronous growth (first fibular phase in 6-7 week, tibial phase in 8-9 week and in fetal period, second fibular phase in post-natal period.