Lethal Yellowing (LY) is one of the most destructive diseases of the coconut (Cocos nucifera L). Although is has been present in Cuba the end of the 19th century. It has not caused severe losses so far. The genetic variability of the associated phytoplasmas and their relationships with others phytoplasmas reported worldwide, as well as the search for possible insect vectors, have been the principal objectives of our work. DNA amplifications using Polymerase Chain Reaction (PCR) were realized on leaf and inflorescence samples from coconuts showing typical symptoms of LY using the universal primers P1/P7 and the specific primers LYF1/LYR1. A 1.8kb product was obtained with P1/P7 giving amplification of the segment 16S-23S rRNA genes and a product of 1.0kb for the non-ribosomal region with the primers LYF1/LYR1. The PCR products obtained with P1/P7 from Cuban isolates of different origins and isolates from Jamaica, Ghana and Mozambique were digested with the restriction enzymes Haelll, RsaI AluI and Hinf I. Great differences were not observed between patterns obtained from the Cuban isolates. Only the Hinf I showed different patterns. PCR products were cloned and sequenced. Sequences were used to determine the genetic variability between Cuban isolates and to compare with other GENBANK sequences from Caribbean and African isolates. A high homology was detected between the analyzed isolates from different regions of Cuba. Nevertheless differences have been found, showing variability among the isolates associated with LY in Cuba. Two planthoppers, Nymphocixia caribbea Fennah and Myndus Crudus Van Duzee (Homoptera: Cixiidae), were found in plantations of coconut palms affected by LY. They can be suspected as potential vector of the phytoplasmas associated with the LY. (Texte intégral)