We drew up a checklist of the Italian vegetation (http://www.prodromo-vegetazione-italia.org/), up to the syntaxonomical rank of alliance. During the compilation of this checklist, we observed that some syntaxa were invalidly published. For this reason, in this article we validated some syntaxa names and, at the same time, described new syntaxa of different hierarchical levels. Therefore, 10 new orders, 1 new suborder, 18 new alliances, 3 new suballiances and 5 new associations are described here. These new syntaxa belong to the following classes: Adiantetea capilli-veneris, Parietarietea judaicae, Thlaspietea rotundifolii, Artemisietea vulgaris, Stellarietea mediae, Galio aparines-Urticetea dioicae, Mulgedio alpini-Aconitetea variegati, Trifolio medii-Geranietea sanguinei, Festuco-Seslerietea, Salicetea herbaceae, Festuco valesiacae-Brometea erecti, Molinio-Arrhenatheretea, Cisto cretici-Micromerietea julianae, Rhamno catharticae-Prunetea spinosae, Salici purpureae-Populetea nigrae, Salicetea purpureae, Quercetea ilicis and Querco roboris-Fagetea sylvaticae