Recent floristic study of the island of Limnos (NE Aegean, Greece) has resulted in the addition of 69 new plant taxa. As a result the flora of the island now comprises 750 taxa. New alien species such as Erigeron sumatrensis, Erigeron canadensis, Symphyotrichum squamatum, Amaranthus retroflexus and Amaranthus blitoides nowadays colonise thousands of hectares of fertile ground and present the highest rates of invasion. Ecological factors such as soil texture, high winds and human intervention, in combination with their seed dispersal mode and genetic background, may explain their successful establishment and impressive abundance especially in the eastern part of the island. Among the new records of indigenous plants are some interesting taxa from a phytogeographical point of view, such as Bupleurum euboeum and the Greek endemic Polygonum icaricum.