To date, 13 viral species belonging to 7 genera have been recorded on olive (Olea europaea). Their correct identification is made mandatory by the quality norms issued by the European Community for the propagative materials of fruit trees (CAC) and the legislative provisions regulating voluntary certification of olive in Italy. Detection techniques used until recently were based on bioassays (mechanical transmission to herbaceous hosts). These techniques, however, proved unreliable as a number of plants that had given negative responses in bioassays were found to contained dsRNAs. Molecular detection protocols were therefore developed which were based upon: (i) a quick method for dsRNA extraction so as to provide an immediate response on the health status of the samples examined; (ii) molecular hybridization (dot blot) of denatured dsRNAs with virus-specific riboprobes; and (iii) one step RT-PCR on crude sap from olive tissues or total nucleic acid (TNA) extracts. The results showed that: (i) dsRNA were found in 210 of 286 olive samples (73.4%) collected from six different Italian regions. Better responses were obtained from samples collected in spring rather than in autumn. Satisfactory dsRNA extraction could be obtained from as little as 5 g of cortical scrapings; (ii) one step RT-PCR yields much better results using TNA extracts than crude sap; (iii) dot blot hybridization of denatured dsRNAs with digoxigenin-labelled virus-specific riboprobes is the most reliable detection method currently available.