The 16S rDNA sequences of the RYD phytoplasmas and related phytoplasmas in the RYD 16S-group (RYD-J, RYD- Th, BGWL-Th, BGWL-KK, BraWL-KK and SCWL-Ud) were compared with sequences from phytoplasmas of other groups. The base positions were numbered as described previously (Namba et al., 1993a).