Summary: For a long time in situ conservation has been the main approach used to protect Chilean plant diversity. However, due to the high level of endemism of its flora (50%) and an increasing human impact on wild areas, ex situ conservation has become an urgent requirement to avoid the extinction of plant populations and species. Since 2001, the Instituto de Investigaciones Agropecuarias (INIA), Chile, has been working in partnership with the Royal Botanic Gardens Kew, (Kew) through the Millennium Seed Bank Project (MSB) with the objective of conserving 20% of the Chilean flora as seeds in long-term storage. This seed conservation effort has focussed mainly on the endangered and endemic plants of the Chilean drylands. Towards the end of the first phase of the MSB some 1482 seed collections representing 850 species and subspecies have been collected and safely preserved in the INIA Seed Base Bank and duplicated at Kew. Almost 70% of the total species collected are endemic to Chile and several of them are endangered. Additionally, seed germination research has been conducted for nearly 400 species and seed collections have been used to propagate several threatened species. Germination protocols have been published and disseminated online. Over 4,500 herbarium vouchers have been collected, largely duplicated at Kew and at the national herbarium in Chile. As a result of the inputs of INIA and the MSB, collaboration has been extended to other national stakeholders, mainly for plant taxonomy and seed collecting. In this context two training courses have been run for 70 staff/students. This training has contributed to the raising of general awareness of the need for the long-term protection of Chilean plant diversity and to demonstrate the key role that ex situ seed conservation can play in meeting this need. © 2011 The Board of Trustees of the Royal Botanic Gardens, Kew.