Technical Abstract: Soybean yellow mottle mosaic virus (SYMMV) is a soybean-infecting virus recently described in Korea that initially induces bright yellow mosaic on leaves followed by stunting and reduced growth of older leaves. Nucleotide sequence analysis of genomic RNA of the Korean isolate of SYMMV suggested that the virus is a new member of the genus Carmovirus in the family Tombusviridae. To determine whether SYMMV is present in the United States, two pairs of oligonucleotide primers were designed from regions conserved between SYMMV and Cowpea mottle virus (a related and seed-transmitted carmovirus) for use in quantitative real-time reverse transcriptase polymerase chain reaction (QRT-PCR) analyses. In August 2008, about 10 leaflets from 10 plants each of 136 plots were collected without regard for symptoms from a research field in Stoneville, Mississippi that contained 17 plant introductions (including five from Korea) and Williams 82. Samples were grouped into pools of 100 leaves from which total RNA was extracted and analyzed by QRT-PCR. Six of the ten 100-leaf pools produced positive signals with both primer sets. Using primers corresponding to nt 1-21 and complementary to nt 3483-3508 and corresponding to nt 3366-3391 and complementary to nt 4000-4009, two overlapping DNA fragments representing the entire SYMMV genome were amplified and sequenced. The 4009 nt sequence (Genbank Accession #____) was 95% identical to the Korean SYMMV isolate and 65% identical to Cowpea mottle virus. This is the first report of Soybean yellow mottle mosaic virus in North America.