The Red Data Book of European Butterflies, published in 1999, showed that butterflies have declined seriously across Europe and that 71 of the 576 species are threatened (12% of the total) either because of their extreme rarity or rapid decline. Many more species were shown to be declining in substantial parts of their range. A follow up project was conducted in 2002–3 to identify Prime Butterfly Areas (PBAs) in Europe where conservation should be targeted as a priority. Due to constraints of time and resources, this concentrated on identifying the most important (prime) areas for 34 target species, using a network of national compilers. The book gives details of 431 areas covering 1.8% of the land surface of Europe, and shows that target butterflies are declining in one quarter of PBAs, indicating that breeding habitats are continuing to deteriorate even though many are protected by national designation. Chief threats are from agricultural intensification, afforestation, abandonment of traditional practices, and isolation. We make nine recommendations: (1) Produce detailed descriptions of the PBAs within each country and protect all PBAs under national law; (2) Protect PBAs under relevant international EU law (e.g. EU Habitats and Species Directive); (3) Provide adequate protection of PBAs in non EU countries; (4) Ensure sound habitat management within PBAs and sympathetic management in surrounding areas; (5) Take measures to conserve the wider environment and whole landscapes within and surrounding PBAs in order to sustain viable metapopulations; (6) Monitor populations of target species and conduct research to identify appropriate habitat management techniques. (7) Revise pan-European legislation to take account of the new information provided in the Red Data Book of European butterflies (e.g. Bern Convention and the EU Habitats and Species Directive); (8) Conduct a more comprehensive review of Important Butterfly Areas in Europe as soon as possible; (9) Keep the list of Prime Butterfly Areas up-to-date (e.g. via the internet).