The Killarney fern is listed on Annexes II and IV of the Habitats Directive and Appendix 1 of the Bern Convention and is listed as rare on the IUCN global Red Data List.

In the UK it is protected under Schedule 4 of the Conservation (Natural Habitats, etc.) Regulations 1994 and Schedule 8 of the Wildlife and Countryside Act, 1981. Accordingly it was made a UK Biodiversity Action Plan (BAP) species in the first tranche (1995) and the Natural History Museum became Lead Partner and contact point. Our work (Rumsey et al., 2003) has helped show that the threat to the species is lower than first believed and as a consequence the species is no longer considered in need of BAP status. It is still an offence to collect or damage the species, or its habitat, under law.

Most sites are unlikely to be easily damaged but hydro-electric schemes, water abstraction, clear felling and some recreational pursuits such as gill scrambling could adversely effect the plant.