Plants of sesame, Sesamum Indicum, with symptoms of mosaic, leaf distortion, chlorosis and dwarfing were detected by field surveys. Cytological studies under the light microscope involving epidermal leaf strips obtained from these plants revealed the presence of cytoplasmic inclusion similar to those induced by potyviruses. The potyvirus isolated from sesame was serologically related to blackeye cowpea mosaic virus, bean common mosaic virus and cowpea aphidborne mosaic virus but did not present any reaction to papaya ringspot virus-W (watermelon mosaic virus-1). The virus systematically infected healthy cowpea and sesame plants mechanically inocualted. In the host range studies, the virus mechanically inoculated. In the host range studies, the virus infected eight out of 14 plant species including S. indicum and 12 cvs. of cowpea, Vigna unguiculata. The virus was also able to infect all 12 cvs. of S. indicum tested, and all virus infections were confirmed by serology. The cytological, serological and biological results indicate that sesame plants were naturally infected by a potyvirus related to blackeye cowpea mosaic virus.