The isometric virus isolated from several lettuce plantations appeared to be dandelion yellow mosaic sequivirus. Despite of some differences it seemed to be closely related to Dutch Ls2 isolate. Identification was based on the host range, physico-chemical properties, electron microscopy and serology. The differences in virus susceptibility were found between 12 cultivars mechanically inoculated. None of approximately 1500 seedlings of 9 cultivars, derived from infected plants, was virus infected.