Abstract:Abstract: Group II introns are both catalytic RNAs (ribozymes) and mobile retroelements that were discovered about 14 years ago. Mobile Group II introns were also found in bacteria recently, and they can either retrohome into cognate alleles that lack the intron or retrotranspose to ectopic sites. We reviewed the main mobility (homing) pathways of bacterial group II introns by describing the relationship between Intron-encoded protein activities and intron mobility. We discussed whether mobility of Cyanobacteria group Ⅱ introns could occur and possible mechanisms of their mobility. Furthermore, the biological implications of groupⅡ introns transferring within a species or among different species are also discussed.