Soybean dwarf virus (SbDV; family Tombusviridae, genus Luteovirus, species Soybean dwarf virus) can cause damaging disease epidemics in cultivated Fabaceae. The biological characteristics of SbDV isolate WA-8, including its vector species, host range and potential impact on Australian grain legume cultivars, were investigated in a series of glasshouse experiments. WA-8 was determined to be a YP strain isolate as it was transmitted by Acyrthosiphon pisum (pea aphid) and Myzus persicae (green peach aphid) and infected known strain indicator species. Of the 18 pasture legume species inoculated with SbDV, 12 were SbDV hosts including eight previously unrecorded as hosts. When inoculated with SbDV, field pea (Pisum sativum), faba bean (Vicia faba), lentil (Lens culinaris) and narrow-leafed lupin cv. Jurien were most susceptible (70 to 100% plant infection rates), and albus lupin (Lupinus albus), chickpea (Cicer arietinum) and narrow-leafed lupin cv. Mandelup were less susceptible (20 to 70%). Over the course of three experiments, chickpea was the most sensitive to infection, with > 97% reductions in dry above ground biomass (AGB) and 100% reductions in seed yield. Field pea cv. Gunyah, faba bean and lentil were also sensitive with 36 to 61% reductions in AGB. Field pea cv. Kaspa was tolerant with no significant reduction in AGB or seed yield. The information generated in this study provides important clues in understanding SbDV epidemiology and suggests it has potential to threaten to grain legume production in Australia, especially if the impacts of climate change promote its spread.