Crested Ibis Nipponia nippon is an Endangered species that has experienced a severe but short-lived population bottleneck in recent years. Only one wild population and two captive populations exist in China today, all of which were probably initiated from two breeding pairs rediscovered in 1981. This paper represents the first study of the genetic diversity of Crested Ibis by analysing sequence variation of a fragment spanning domains II and III of the mitochondrial DNA (mtDNA) control region of both wild and captive populations. Two haplotypes were identified in both wild and captive populations, and the captive population had a bias towards haplotype 1. The species as a whole demonstrated an extremely low level of genetic diversity, with a haplotype diversity and nucleotide diversity of 0.386 ± 0.074 and 0.069% ± 0.013%, respectively. Despite the rapid increase in numbers of birds under intensive management, the paucity of genetic diversity remains a real threat to the species. The mtDNA control region variations detected in the present study could provide significant information additional to the studbook data of Crested Ibis; therefore we suggest that special attention be paid to individuals with haplotype 2 when considering captive breeding management. Overall, great care should be taken in the selection of reintroduction sites for this rare bird, as species with low genetic diversity are thought to be more limited in their ability to tolerate a wide range of environmental extremes and diseases.