Three unlinked genes ARGRI, ARGRII and ARGIII are necessary to control the synthesis of the arginine anabolic and catabolic genes. The three genes have been cloned and sequenced and we report here the results for the ARGRI and ARGRIII genes. They encode proteins of 177 and 355 amino acids, respectively. The ARGRIII protein has a very acidic carboxy-terminus (17 aspartate residues). From a comparison of the sequences, the ARGRI and ARGRIII gene products do not show the common characteristics of other DNA binding proteins (nuclear localization and putative DNA binding site) in contrast to the ARGRII regulatory protein. The transcription of both genes is not affected by the presence of arginine in the growth medium.