Chloroplast transformation in plants has many advantages over nuclear transformation.Proteins in chloroplasts can be expressed at high levels with proper folding and disulfide bonds as the cells of higher plants contain a large number of chloroplast genomes.Multiple genes can be co-expressed in chloroplast genomes.Furthermore,chloroplast genes are inherited in a strictly maternal fashion in most angiosperm plant species,and this minimizes the possibility of out-crossing transgenes to related weeds or species.In addition,gene silencing,position effects and random integration have not been reported in chloroplast transformation.Although chloroplast transformation is very attractive,this technology is not as widely used as nuclear transformation.It has been mostly focused on 16 plants species,especially tobacco in which many proteins has been expressed including vaccines and antibodies.In this review we briefly summarize the rationales,methodologies,applications,bottlenecks and prospects of this promising genetic engineering technology for chloroplasts.