Although increasingly sophisticated methods have been used to research the ecology of felids, such as radio-telemetry and photo-traps, the conservation status of many species is not known. The destruction, fragmentation and erosion of natural habitats poses a serious threat to cat populations. A review by the Cat Specialist Group of the World Conservation Union (IUCN) has indicated that information on the natural history of most felid species is limited. This paper summarizes the status of big cats and lesser cats, and includes species for which there is limited information. It describes some of the conservation measures, such as the control of poaching and the illegal fur trade, and the development and maintenance of nature reserves, which incorporate the interests of humans and felids, which will need to be implemented if felids are to survive.