Distribution of Toscana virus (TOSV) is evolving with climate change, and pathogenicity may be higher in nonexposed populations outside areas of current prevalence (Mediterranean Basin). To characterize genetic diversity of TOSV, we determined the coding sequences of isolates from Spain and France. TOSV is more diverse than other well-studied phleboviruses (e.g.,Rift Valley fever virus). ; Journal Article; Research Support, N.I.H., Extramural; We thank all members of the Red de Enfermedades Víricas Transmitidas por Artrópodos y Roedores, a multidisciplinary group founded by the Fondo de Investigaciones Sanitarias, Spanish Ministry of Health (G03/059), which has partially funded this work, for their constructive discussions, comments, and advice. This study was supported in part by National Institutes of Health awards AI062705, AI051292, AI059576, HL083850, and AI57158 (Northeast Biodefense Center–Lipkin). ; AI051292, NIAID NIH HHS, United States;AI059576, NIAID NIH HHS, United States;AI062705, NIAID NIH HHS, United States;AI57158, NIAID NIH HHS, United States;HL083850, NHLBI NIH HHS, United States;