A strain of raspberry ringspot virus from Scotland (RRV-S) was transmitted frequently by Longidorus elongatus but only once by L. macrosoma. A strain from England (RRV-E) associated in the field with L. macrosoma was infrequently transmitted by each nematode species. In investigations to determine the reasons for this, most L. macrosoma used were shown to have fed on the source plants and many had ingested the virus. Most nematodes exposed to the 2 strains of virus had fed on the roots of the Petunia hybrida bait plants and particles, thought to be those of the virus, were seen, by electron microscope examination, in the region of the anterior odontostyle. Most nematodes seem to have had ample opportunity to transmit virus and the low frequency of transmission may have been due to the failure of the particles to be released from the retention site or to a lack of infectivity of the virus when L. macrosoma is the vector and P. hybrida the host.