The leaves used in these study were obtained from naturally diseased wheat in Lao Shah area,Shah Tung province.Symptoms appeared soon after wheat had turned green in the early spring,showing chlorotic short streaks along the axis of the leaves,stunting,dwarfing and yellowish plants failed to ear.The virus particles,with rod shape,120~270nm in length and 18~20nm in diameter were frequently observed in the narrow peripheral cytoplasm and most of them seemed to be attached to the membrane.When sectioned transversely the virus particle showed an electron-transparent hollow core 10nm in diameter,surrounded by a densely stained ring of nucleic acid which encircled in turn by a less dense outer coat protein.Cluster of virions were usually associated wilh tubules.Crystalline aggregates consisting completely of virus particles were seen.Based on above observations,the viral pathogen was preliminarily identified as the soil-borne wheat mosaic virus.