The earth currently suffers from a bout of animal extinctions. The Frozen Ark Project is acting internationally in preserving the genetic resources of threatened wild species before they become extinct. Modern techniques make preservation of this material easier, and costs of sequencing genomes have declined drastically during the past 10 years. The project is vital because the extinction of a species results in the loss of not only the animal but also the genetic information accumulated over millions of years of evolution. It will give us the ability to invigorate conservation-breeding programmes and conserve material of practical value in the form of tissues, viable somatic cells, gametes, eggs and embryos. The Frozen Ark is not considered a substitute for saving the animals themselves but an essential ‘back-up’ to this activity. International collaboration between the world's zoos, aquariums, museums and universities is developing to achieve this conservation effort of last resort. Zoos and aquariums are crucial to the project because they increasingly hold the last individuals of the most threatened species.