Abstract : World-wide, about 200,00 people are hospitalized with Hemorrhagic fever with renal syndrome (HFRS) (3-10%fatality) each year. The etiologic agents of HFRS are Hantann, Seoul and Puumala viruses of the genus Hantavirus, family Bunyaviridae. A severe form of HFRS, caused by Hantann virus, occurs in Asia and eastern parts of Europe, a moderate form, caused by Seoul virus, occurs in Asia, and a mild form, caused by Puumala virus, occurs in Europe. The reservoirs of hantaviruses are rodents and other small mammals. Global surveys of the distribution of hantaviruses and surveillance of HFRS are important for prevention of this highly fatal disease. A simple and rapid serologic diagnostic test for HFRS in the areas where hantaviruses exist is urgently needed. It is also important to investigate antigenic differences of strains of Hantavirus isolated from rodents caught in on-endemic areas of the world because HFRS patients have never been documented in many areas despite the finding of positive rodents there. The methods of diagnosis of HFRS, isolation of hantaviruses from man and rodents are described previously. A new high density silicone particles were used for a rapid serologic diagnostic test for HFRS. There were 430 cases of HFRS in Korea in 1989 and large outbreaks of scrub typhus, spotted fever and leptospirosis occurred before and during the epidemic season of HFRS. Antibody against hantaviruses was measured within forty minutes by a passive agglutination procedure using high density composite particles coated with purified Hantann virus antigen.