Key aspects of gene transcription regulation in multicellular organisms, including the characteristics of their promoters, transcription-factor binding sites, and composition elements are reviewed. The functional role of transcription regulatory proteins (basal factors and regulatory transcription factors), and the mechanisms responsible for regulation of their activity are also discussed. Furthermore, we describe the importance of DNA-encoded nucleosome organization and chromatin modifications in the course of transcription regulation, as well as some mechanisms that regulate the activity of transcription factors associated with genetic networks. The current outlook on regulatory gene expression codes in eukaryotes is presented.