Georgiades (1994) records 152 adventive species for Cyprus, out of which the following 16 species were regarded as spreading to natural habitats:Vinca major L.,Cistus ladanifer L.,Tagetes minuta L.,Tanacetum balsamita L.,Tanacetum parthenium (L.) Sch.Bip.,Corylus maxima Mill.,Iris albicans Lange,Acacia saligna (Labill.) H.Wendl.,Robinia pseudoacacia L.,Epilobium angustifolium L.,Oxalis pescaprae L.,Eschscholzia californica Cham.,Papaver somniferum L.,Dodonaea viscosa (L.) Jacq.,Antirrhinum majus L.,Vitis vinifera L. We reexamined the spreading status of these species and we found thatAcacia saligna (Labill.) H.Wendl. is the most serious invasive species on Cyprus, threatening many natural habitats, invading forests, maquis, gangue, phrygana, marshy areas and agricultural land, becoming a serious weed.Robinia pseudoacacia L. similarly toAcacia saligna, but to a less extend is spreading in forests, maquis, garigue and phrygana vegetation. Apart from the above species, we observed for the first time that the following adventive species (Georgiades, 1994) are spreading in natural habitats, namely:Celtis australis L.,Cercis siliquastrum L.,Prunus dulcis (Mill.) D.A.Webb,Ailantus altissimma (Mill.) Swingle andCasuarina cunninghamiana Miq. The spreading status ofAilanthus altissima threatens natural habitats invading forests and maquis. Further moreFraxinus angustifolia Vahl subsp.angustifolia, Pyrus malus L. andPrunus persica (L.) Batasch are new additions to the adventive flora of Cyprus, recorded for the first time. These three species are also spreading in natural habitats. Also, the problems posing to the environment and to biodiversity are discussed.