Abstract: Soybean Mosaic potyvirus (SMV) is highly prevalent in major soybean growing areas of the NWFP. Infected plants exhibited predominantly mosaic and mottling symptoms on leaves and stunted growth due to shortened petioles and internodes. Incidence of the virus ranged from mild to severe infection between 8-72% in areas surveyed. ELISA test further confirmed the incidence of the virus from 7 to 64% in major soybean growing areas of the province, during summer 1997-98. Twelve soybean mosaic virus isolates were collected from soybean crop grown in different areas on the basis of characteristic and distinguishable mosaic and mottling symptoms. Isolates, SMV-S1, S2, S3 from Swat and SMV-P1, P2, P3 from Peshawar were further selected on the basis of severity of symptoms and characterized. SMV-S1, 52, 53 produced severe mosaic on mechanically inoculated soybean (Glycine max) cv. Weber-84, leaf chlorosis and chlorotic local lesions on Phaseolus valgaris and P. lunatus and local lesions on Chenopodium amaranticolor and C. quinoa. SMV-P1, P2 and P3 isolates differed from Swat isolates by producing mild mosaic on soybean cv. Weber-84. Isolate SMV-S1 produced severe mosaic, followed by severe mottling, necrosis and occasionally death of plants Weber-84 inoculated with serially diluted sap from infected soybean plants while SMV-P1 caused mild to moderate mosaic symptoms. The dilution end points of both isolates was 11512. Mean A405,,,,, ELISA values of SMV-S1, 52 and S3 was 1.919 and of SMV-P1, P2 and P3 was 1.377, respectively, after overnight incubation of antigen with substrate solution at 4°C. Among these isolates, SMV-S1 showed maximum A405,in values (1.987) followed by SMV-P1 (1.477), respectively.