Halophytophthora fluviatilis, a novel species from inland freshwater in Virginia, is characterized and described in this study. This homothallic species produced ovoid to globose sporangia, which release zoospores directly through exit pores. It grew well in a relatively wide range of salinity from 1.8 to 19.0 parts per thousand. Sequence analysis of the rRNA internal transcribed spacer region placed this new species in the Halophytophthora sensu stricto clade. Description of this new species expanded the habitat to include geographically distinct inland freshwater ecosystems for the genus Halophytophthora, challenging the notion that this genus is marine or brackish. The need to construct a molecular-based taxonomy for the genus Halophytophthora is also discussed.