Over the past ten years, the discovery and functional characterisation of murine Hox genes has led to a better understanding of some of the molecular mechanisms underlying limb development. It has also shed some light on the potential genetic events which have accompanied the fin-to-limb transition, an evolutionary step of critical importance which opened the way to the evolution of higher vertebrates. This convergence between developmental biology and the sciences of evolution is one of the synergistic interface that has been established recently thanks to the use of genetic engineering and transgenic animals. The increasing number of human genetic syndromes which are derived from mutations in developmental control genes remind us that many human genetic diseases are nothing else but alterations in our developmental programme. Here, we illustrate these various issues by discussing the function of Hox genes during limb development.