Analysis was made of dsRNA in 37 cultivars and species of Ribes, that were healthy, naturally affected with the virus-like diseases, black currant yellows, black currant infectious variegation, gooseberry veinbanding or black currant reversion, or graft-inoculated with scions from such diseased plants. Various dsRNA species, differing in size (from ca. 2 to 11 kbp), number and staining intensity in gels, were detected in some or all assays of all plants, including those held as virus-tested stock. In different plant tissues from individual plants, the dsRNA species were usually similar in size and number but, in some sources, the dsRNA profile from flowers and/or bark differed greatly from the profiles of dsRNA obtained from leaves. No dsRNA species were associated consistently with any of these diseases. A 499 kbp cDNA probe was obtained that in Northern blot analysis was specific to a ca. 5 kbp dsRNA species present in the black currant cv. Baldwin. It also detected a similarly sized dsRNA species in plants of many other black currant cultivars, but it did not react with a similarly sized dsRNA species in red currant and gooseberry tissues. The 156 amino acid sequence encoded by the cDNA was very similar to sequences in the RNA-directed RNA polymerases of virus species in the family Totiviridae, especially Saccharomyces cerevisiae viruses L-1 and L-A. The significance of these findings and the possible origin of these dsRNA species are discussed.