Adult golden hamsters inoculated subcutaneously with either of two sandfly fever group viruses, Punta Toro and Gabek Forest (Phlebovirus, Bunyaviridae), developed a fulminating fatal illness characterized by hepatic and splenic necrosis and interstitial pneumonitis. Most animals died within three days after infection; this was accompanied by high levels of viremia. Necropsy and histopathologic examination of the infected animals revealed pathologic changes involving multiple organs that resembled those described in Rift Valley fever. These two hamster-phlebovirus systems may serve as alternative animal models for Rift Valley fever and should be useful in studying the pathogenesis of severe phlebovirus infection and for testing potential therapeutic agents.