In this paper, we try to define the extent of antigenic variation between dengue-2 viruses from Hainan province, which had been isolated over a period of 3 years (1985-1987). The dengue-2 viruses were compared with the prototype New Guinea B strain and were subjected to antigen signature analysis. Eight strains of dengue-2 virus were analyzed by three monoclonal antibodies: flavivirus group, subcomplex dengue-2 type-specific reactive epitopes, over a range of antigen concentration. Five out of eight dengue-2 virus strains showed them to be antigenically homogeneous, and the remaining three strains showed them to be heterogeneous. Signature analysis provides a rapid and simple means to different strains derived from different sources, thus permit monitoring changes or introductions of hew dengue virus populations in certain geographic region.