In the course of the project “Syntaxonomic checklist of the Italian classes, orders and alliances (Vegetation Prodrome of Italy)”, promoted in 2012 by the Italian “Ministry of Environment, Land and Sea Protection” in collaboration with the “Italian Society of Botany”, it arises that some syntaxa are not validly published according to the International Code of Phytosociological Nomenclature rules. For this reason, these syntaxa names are validated in the present paper. Furthermore, other new syntaxa of different hierarchical levels are here described for the first time. Therefore, 1 new order, 2 new suborders, 6 new alliances, 2 new sub alliances and 3 new associations are here described. These new syntaxa belong to the following classes: Juncetea maritimi, Stellarietea mediae, Trifolio medii-Geranietea sanguinei, Alnetea glutinosae and Salici purpureae-Populetea nigrae. Finally, the syntaxonomic arrangement of Alnion incanae is here discussed.