Technical Abstract: Lettuce necrotic stunt virus (LNSV) causes lettuce dieback, a disease resulting in stunting, necrosis, and lack of marketability in lettuce, and likely was present under the name brown blight since the 1920s. In order to clarify the relationship of LNSV to Tomato bushy stunt virus (TBSV), another virus known to cause lettuce dieback, and other tombusviruses affecting western U.S. lettuce production, the genome of LNSV was sequenced and compared with related virus species. Results indicate a genome of 4772 nucleotides, with six open reading frames, and organization typical of viruses in the genus, Tombusvirus. Sequence comparisons indicated much of the genome is most closely related to TBSV; however, the coat protein is identical to that from an isolate of Moroccan pepper virus (MPV) from Iran. Tombusvirus coat proteins vary widely among species. MPV is a partially characterized tombusvirus first identified in 1975 in Morocco, and subsequently in Germany, Italy, and Iran. These results warrant further characterization of MPV, and raise questions of how a virus responsible for a disease affecting California lettuce for nearly a century would show near identity in a divergent region of the genome with a tombusvirus from the Old World.