A mosaic disease of sunflower (Helianthus annuus L.) was reported by Venugopal Rao et al. (1987) and etiological agent was found to be cucumber mosaic virus. Three species of aphids, Aphis gossypi Glov.; Aphis craccivora Koch, and Rhopalosiphum maddis Fitch. were found to be vectors of the virus. Further investigations were carried out to find out the other possible vectors and on the relationship of causal virus with the aphid A.gossypii which was proved to be the most efficient vector and the results of these studies are being reported herein.