RNA editing is a process in which the genetic information of a gene transcript is changed during or after transcription. RNA editing exists extensively in the higher plant mitochondria, and is a necessary step for forming functional proteins. There may be some relationship between RNA editing and cytoplasmic male sterility (CMS), a kind of phenomenon that is closely associated with mitochondrial genome mutations. The research materials were the gametopthyte male sterility line(A), maintainer line(B) and F₁ hybrid(F₁) of HL-type CMS. cDNAs and DNAs of atp6 were obtained from A, B and F₁ by PCR and RT-PCR. Then sequences of cDNAs and DNAs are compared: A, B and F₁ share the same 15 editing sites found in the transcripts of atp6. The restorer gene in F₁ greatly changed the editing frequency of each editing site. So it is suggested that HL-type CMS is associated with RNA editing of atp6.