A plant short interspersed element (SINE) was identified in Glycine max after re-sequencing of the soybean sequence characterized amplified region (SCAR) markers. Detailed analysis revealed that this newly recognized SINE element consisted of a tRNA-related region, a tRNA non-related region, direct flanking repeat sequences, and a short stretch of Ts at the 3'-terminal region. These features are similar to previously characterized SINEs. To investigate the evolution of the SINE retroposon, BLASTN was used to search against genome sequences of other plants. Since it is homologous with the retroposon Au in Aegilops umbellulata (wheat) and its homology in soybean, the SINE is named as GmAu1. Genome analysis of the Glycine max var. Willimas 82 uncovered more than 847 copies of GmAu1 per haploid genome of soybean. Examination of the regions flanking the inserted GmAu1 sequences indicated a preference for introns over exons or other noncoding regions. Considering the flanking insertion sequences, 146 primers were designed in order to detect insertion mutations by a PCR-based method. Seventy-seven primers displayed polymorphism and were used to develop corresponding GmAu1-based SCAR markers. The retroposon GmAu1 and its related SCAR markers identified in this study will prove valuable to future investigations into the genetic mapping, phylogeny, and evolution of the Glycine genus.