During development, transcription factors are necessary not only to pattern the body plan but also to control growth. However, the link between these two developmental components has been difficult to establish. Hox genes are involved in the emergence of a functional digestive system in metazoans, thus providing a potential impact on growth through nutrition. Also, genetic conditions involving these genes lead to important growth retardation. We analyzed several targeted mutant lines at the HoxD locus and found that stunted phenotypes can all be explained by the lack of function of Hoxd3 , whose role seems to be critical in the developing gut of suckling mice, perhaps as an adaptation to the milk-dependent early postnatal period in mammals.