Sex-determining mechanisms are highly variable between phyla. However, there is an apparent exception in which structurally and functionally related genes control sex determination in different phyla: the sexual regulators DSX of Drosophila melanogaster and MAB-3 of Caenorhabditis elegans both containing a DNA-binding motif, DM domain. Proteins containing the domain may also play a role in sexual development of vertebrates. For examples, both the human DMRT1 (doublesex and mab-3 related transcription factor 1) gene and mouse Dmrt1 gene are necessary for male development. In this paper, through the degenerated PCR, a DNA fragment ADM was amplified out from genomic DNA of brine shrimp, Artemia sinica from YunCheng Salt Lake, Shanxi, China and Artemia parthenogenetica from GaHai, Qinghai, China, respectively. ADM encodes 47 amino acids and is highly homologous to amino acid sequence of the known DM domains. By comparing total of 27 DM domains in distant related species, a phylogenic tree of DM domain was constructed. In the tree, these DM domains were divided into different branches according to their subtypes. Among the DM domains that were compared, ADM is most homologous to the DM domain contained in human DMRT3 and mouse Dmrt3, which shares 83% identity between them. In addition, the same length of ADM could also be amplified out from cDNA of Artemia sinica and Artemia parthenogenetica, which indicated that ADM was expressed and located in one exon. The DM domain in brine shrimp reported here would make it possible for cloning the full-length cDNA containing the DM domain and further elucidating their functions.