In this paper we present a comprehensive inventory of the non-native vascular flora of Italy, which was produced within the project “A survey of the Italian non-native flora”, funded by the Italian Ministry for the Environment. Previously published floristic accounts were the main source of information. Historical records were critically revised and integrated with recent literature, data from herbaria and some unpublished information, so as to obtain a complete, up-to-date catalogue of the non-native vascular plant species that occur spontaneously in Italy. The inventory lists 1023 non-native species and subspecies, which account for 13.4% of all the Italian flora. The Italian non-native flora was divided, according to its residence time, into 103 archaeophytes and 920 neophytes. According to its current invasion status, it was classified into 437 casual (42.7% of all non-native) and 524 established taxa, the latter being divided into 361 naturalized noninvasive (35.3%) and 163 invasive taxa (15.9%). The inventory includes a group of 62 species (6.1%) that lack recent records (i.e. since 1950). By combining local expertise into a unified, nationwide scheme using a standardized method and terminology, the inventory provides the essential scientific basis for the development of plant invasion research and management in the country.