The Maf family proteins, which constitute a subgroup of basic region-leucine zipper (bZIP) proteins, function as transcriptional regulators of cellular differentiation. Together with the basic region, the Maf extended homology region (EHR), conserved only within the Maf family, defines the DNA binding specific to Mafs. Here we present the first NMR-derived structure of the DNA-binding domain (residues 1-76) of MafG, which contains the EHR and the basic region. The structure consists of three alpha-helices and resembles the fold of the DNA-binding domain of Skn-1, a developmental transcription factor of Caenorhabditis elegans. The structural similarity between MafG and Skn-1 enables us to propose a possible mechanism by which Maf family proteins recognize their consensus DNA sequences.