Preserving the native fauna and flora of Antarctica is a legal obligation on Antarctic Treaty signatory countries by the Madrid Protocol. This report addresses threats to the native biota that alien species present, particularly those with invasive characteristics. Historically, protection against alien species’ invasion has been achieved through increasingly rigorous and effective quarantine inspection procedures of people and cargo leaving for the territory. In recent years, monitoring has been recognised as important for identifying those species which slip through inspections, and there is increasing recognition of the need to formulate effective and unified response plans. This essay discusses these issues generally in the context of continental Antarctica, and goes on to relate them to specific needs identified as relating to New Zealand’s Scott Base. Invasive species from viruses, bacteria and algae to plants and small animals are considered. Recommendations are made for improvements in prevention, monitoring and response to preserve the Ross Island region in particular. These include suggestions for improving the Base’s reporting system for insect incursions, for effective monitoring of plants in the base vicinity and beyond, and the need for a fulltime biosecurity post. Key issues are identified that may form the basis of a comprehensive response plan, including the methods by which alien species can be reliably identified, how they should be 2 dealt with, and whether herbicides and pesticides might be acceptable solutions to curb their spread. Finally, the report considers areas in which more research is required before recommendations can be made. Knowledge is particularly lacking with regard to the smallest inhabitants of Antarctica, the microbiota.