Abstract: To investigate the distributions and functions of RNA editing sites in tobacco mitochondria, the genome and transcriptome sequencing data from tobacco roots, flowers and leaves were analyzed to identify the RNA editing sites that converted cytosine (C) to uracil (U) in tobacco mitochondria. The results showed that 4 212 RNA editing sites in tobacco mitochondria were identified, wherein 30.2% editing sites were located in protein-coding genes and rps3, mat-R and ccmFN were the protein-coding genes with the highest number of editing sites. There were 62 RNA editing sites belonging to nonsense mutations or mutations that resulted in stop codon loss. Comparing the number of the editing sites in tobacco roots, flowers and leaves, the leaves had the highest number (2 923) of editing sites. The analysis of the RNA editing sites for nonsense mutations in the 3 organs suggested that the genes where these sites were located in were involved in the biological process of electron transport in the oxidative respiratory chain and protein synthesis. In total, 553 RNA editing sites were located in open reading frame genes, which indicated that these open reading frame genes might be involved in some functions of mitochondria.