A virus isolated from sorghum in Venezuela in Aug. 1980 was identified as maize dwarf mosaic virus. The virus caused a severe reaction in 7 sorghum cultivars resistant to maize dwarf mosaic virus, particularly Tx2536 and RTx430, but did not infect the immune QL3 and QL11. The virus infected Johnsongrass [S. halepense] and was serologically related to maize dwarf mosaic virus but not to sugarcane mosaic virus A or H. It is proposed that the Venezuelan virus is a variant of maize dwarf mosaic virus strain A.