Psyllids are potentially a good model group for investigating co-speciation with their host plants as well as biogeographical patterns due to their narrow host and geographical ranges. A major problem is the taxonomic and phylogenetic base which is still absent or unstable in many psyllid groups. The paper gives an overview of the histery of psyllid systematics and summarises present knowledge. The knowledge is uneven with regard to taxa and biogeographical regions. Finally areas are suggested areas for future research.