Basic helix-loop-helix (bHLH) transcription factors have been shown to be important regulatory proteins for tissue determination and differentiation. We cloned the chicken homologue of the gene of the murine Twist-related bHLH protein Dermo-1, which we named cDermo-1, and analyzed its sequence and embryonic expression. Our sequence data suggest a decisive role of Dermo-1 proteins in the evolution of amniote skin. We present a detailed analysis of cDermo-1 expression during avian embryonic development. cDermo-1 is first expressed in a variety of mesodermal tissues of the chick embryo including the limb buds, but later becomes restricted to the subectodermal mesenchyme of the integument and the developing feather buds, indicating a role of cDermo-1 during avian skin and feather development.