Hantaan viruses cause haemorrhagic fever with renal syndrome (HFRS), resulting in severe morbidity and mortality in humans. The genome of Hantaan virus is composed of three segmented and single stranded negative sense RNA genome. In this study, we expressed nucleocapsid (N) proteins of Hantaan 76-118, Seoul 80-39 and Hantaan virus isolated in Korea (01-23) using E. coli system. These N proteins were fused with a thioredoxin protein for secretion of the expressed protein. The antigenicity of each expressed N proteins was examined in Western blot with sera from HFRS patients and normal controls. The expressed N proteins did not show any cross-reactivity with sera obtained from patients with leptospirosis and tsutsugamushi disease. These results suggest that our recombinant N proteins can be used for the development of diagnostic system to distinguish between HFRS and leptospirosis or tsutsugamushi.