The flocculation test using high density latex (HDLF) which gives a reaction figure very similar to that of sensitized sheep red blood cells was established for simplified detection of rice stripe virus from infected rice plants and viruliferous insect vectors. Furthermore, six other plant viruses such as rice dwarf virus, odontoglossum ringspot virus, cymbidium mosaic virus, turnip mosaic virus, carnation mottle virus and cucumber mosaic virus were detected by HDLF of each infected host. These dilution end points for the positive reaction of sap were 1:8×103 to 1:16×103. Though weak non-specific reactions of HDLF were observed in sap from some healthy plants, they could be prevented by diluting sap more than 1:100.