Abstract
Alien invasive species (AIS) is one among the various threats to the biodiversity of Sri Lanka. A survey was carried out to establish the present status of AIS in Sri Lanka. Wetland and terrestrial ecosystems of different climatic zones were surveyed randomly for the presence of AIS and their threats. Among the 59 AIS identified, 10 species of fauna and 13 species of flora are included in the list of 100 of the world's worst AIS. The alien invasive fauna of Sri Lanka includes 15 vertebrates and 5 invertebrates. The paper discusses the impact of alien invasive fauna and flora on the native species and stresses the need for a proper management strategy.