This report describes the first investigation of clinical findings for a larger series of patients with hemorrhagic fever with renal syndrome (HFRS) who were infected with Dobrava virus. From 1985 to 1995, 38 patients with serologically confirmed HFRS were hospitalized at the regional hospital in Novo mesto in the Dolenjska region of Slovenia. On the basis of results of serological examination, 24 patients had Dobrava virus infection, and 14 patients had Puumala virus infection. Complete clinical data were available for 31 patients. Eleven patients underwent hemodialysis for treatment of acute oliguric or anuric renal failure. Four patients, all infected by Dobrava virus, had signs of shock and severe bleeding. Three severely ill Dobrava virus-infected patients died of hemorrhagic complications. We have demonstrated that Dobrava and Puumala viruses coexist in a single region of endemicity and are capable of causing HFRS with significant differences in severity.