Three extraction media for the isolation of nucleic acids from grapevines, a tissue high in polyphenols and other materials that interfere with nucleic acid extraction, were compared. When phenol was present in the initial extraction media only a small yield of soluble RNA and no high molecular weight rRNA was obtained. In the absence of phenol in conventional salt and detergent-based extraction media, rRNAs were extracted, but a major proportion of the RNAs were broken down. Using Na-perchlorate, a chaotropic salt, in a rapid procedure, it was possible to extract both high and low molecular weight RNA efficiently. This procedure enabled the detection of viral RNA, which could not be detected following phenol extraction, at the picogram levels, by dot-blot hybridization.