<p>We discuss several aspects of the alien flora of Campania (southern Italy), on the basis of an updated and annotated checklist. The non-native flora includes at present 346 taxa in 231 genera, representing 82 families. However, other 55 taxa were not found later than 1950. Trends in alien plants invasion throughout the investigated area are discussed. Results are therefore compared with similar data from other Italian regions and other European countries. In the Appendix, taxa are listed with essential synonymy, local and general distribution, status, biological form, habitat, diffusion mechanisms, potential threats, literature data, voucher specimens, and miscellaneous ethnobotanical, chronological and taxonomical notes. In addition, 49 escaped taxa are known only for Botanical and private gardens, while 66 taxa are regarded as doubtful aliens. By including also these two categories, the non-native flora of Campania reaches 516 taxa. In addition, numerous doubtful and erroneous indications were discussed. Finally, a reference list for the exotic regional flora from 1500 C.E. to present is proposed.</p
