Laos is an important country for bird conservation. Bird surveys between 1992 and 1996, the first since 1949, covered 20 main areas, with incidental records from many others. This paper reviews the status of all Lao species reported to be of elevated conservation concern (key species) in any of the following categories: Globally Threatened or Globally Near-Threatened (sensu Collar and Andrew 1988 and Collar et al. 1994), and At Risk or Rare in Thailand (sensu Round 1988 and Treesucon and Round 1990). Several additional species are covered which have clearly undergone a National Historical Decline in Laos. A comprehensive review of other Lao species was not possible, and some species which are in truth of conservation concern have doubtless been overlooked. Historical and modern records were reviewed and population trends identified where possible. Current global status listings (Collar et al. 1994) were supported, except that consideration should be given to changing Red-collared Woodpecker Picus rabieri and Sooty Babbler Stachyris herberti from Threatened to Near-Threatened. If the Lao situation is representative of the species throughout their range, then consideration should also be given to placing Ratchet-tailed Treepie Temnurus temnurus and River Lapwing Vanellus duvaucelii as Near-Threatened. Twenty-seven Globally Threatened species are known from Laos, of which there are recent records of 22. There are recent unconfirmed records of two more. Forty-seven Globally Near-Threatened species are known from Laos, of which there are recent records of 39; there are unconfirmed records of one further species. Five Globally Threatened and five Near-Threatened species were recorded for the first time in Laos in recent years, suggesting that further species of elevated conservation concern remain to be found. All species reviewed were placed in one of the four categories: At Risk in Laos, Potentially At Risk in Laos, Little Known and Not At Risk in Laos. These are assessed in the light of foreseeable threats; some species may move into a higher category of threat in due course. Forty-four species are thought to be At Risk in Laos; there are no recent records of four of these. Twenty-five species are thought to be Potentially At Risk in Laos; there are no recent records of two of these. Thirty-four species considered by this review are thought to be Not At Risk in Laos at the current time, whilst there is insufficient information to make an assessment (termed Little Known) for another 32 species. Laos retains a much higher proportion of forest cover than do most neighbours, including substantial lengths of almost pristine riverine forest in the Nam Theun and Xe Kong basins, extensive level lowland forest (especially at Xe Pian National Biodiversity Conservation Area and Dong Khanthung Proposed Protected Area in the South) and considerable amounts of slope forest at all altitudes. At least 27 forest species seem to occur in globally significant numbers. This is probably because the surveyed forests were large in relation to hunting and degradation pressures on the populations of most species. Logging of virgin areas, hydropower schemes and clearance of forest for cultivation will soon reverse this situation unless controls are established. At least 35 of the species under consideration have declined over the past 50 years by a magnitude exceeding that of their habitat loss, so that they are now absent from large areas of suitable habitat. Twenty-four of them are associated with slow-flowing rivers and other wetlands. These areas are preferentially settled and exploited by people and their birds are thus under elevated threat from hunting, habitat clearance and disturbance. Other factors may explain the declines of several birds (Pied Kingfisher Ceryle rudis and Plain Martin Riparia paludicola) in these habitats. Most other decreasing species inhabit open deciduous forest or scrub, which also experience heavy human use. Hornbills, however, occupy dense forest but also have declined, perhaps because their conspicuousness, flocking behaviour and low reproductive rate all magnify the effects of hunting. Further species have doubtless declined, but historical data are too patchy to demonstrate this. The major threats to birds in Laos include logging, accelerated forest clearance and fragmentation on a large scale (for subsistence and commercial purposes), intensification of wetland use and widespread unrestricted hunting. A new force with the potential to be exceedingly damaging is a proposed programme of over 50 hydropower developments. These will inundate and fragment large areas of intact habitat, force farmers to clear fresh land elsewhere and open up access to some of the nation's most remote and pristine wildlife habitats. Conservation measures will revolve around implementing management within the recently established protected areas, resisting commercial exploitation within them, and expanding the network to cover currently under-represented habitats. For a few species, measures beyond the reserves system are imperative: these include species requiring large rivers (e.g. Great Thick-knee Esacus recurvirostris, terns and River Lapwing) and wide-ranging large waterbirds (e.g. storks, ibises and cranes). Further status surveys for all species are needed throughout Laos and are particularly urgent for large waterbirds and everywhere in North Laos. In a global context, Laos has highly important populations of: Siamese Fireback Lophura diardi, Crested Argus Rheinardia ocellata, Green Peafowl Pavo muticus, White-winged Duck Cairina scutulata, Red-collared Woodpecker, Red-vented Barbet Megalaima lagrandieri, Brown Hornbill Anorrhinus tickellii, Rufous-necked Hornbill Aceros nipalensis, Blyth's Kingfisher Alcedo hercules, Coral-billed Ground-cuckoo Carpococcyx renauldii, Masked Finfoot Hdiopais personata, Grey-headed Lapwing Vanellus cinereus, Lesser Fish-eagle Ichthyophaga humilis, White-rumped Vulture Gyps bengalensis, Long-billed Vulture Gyps indicus, Red-headed Vulture Sarcogyps calvus, Rufous-winged Buzzard Butastur liventer, White-shouldered Ibis Pseudibis davisoni, Giant Ibis P. gigantea, Greater Adjutant* Leptoptilos dubius, Blue-rumped Pitta Pitta soror, Bar-bellied Pitta P. elliotii, White-winged Magpie Urocissa whiteheadi, Yellow-breasted Magpie Cissa hypoleuca, Ratchet-tailed Treepie, Green Cochoa Cochoa viridis, Jerdon's Bushchat Saxicola jerdoni, Beautiful Nuthatch Sitta formosa, Black-hooded Laughingthrush Garrulax milleti, Grey Laughingthrush G. maesi, White-cheeked Laughingthrush G. vassali, Red-tailed Laughingthrush G. milnei, Sooty Babbler, Grey-faced Tit-babbler Macronous kelleyi, Spectacled Fulvetta Alcippe ruficapilla, Rufous-throated Fulvetta A. rufogularis, Mountain Fulvetta A. peracensis and Short-tailed Parrotbill Paradoxornis davidianus. These are species either on the brink of global extinction; Globally Threatened or Near-Threatened but occurring commonly at many sites in Laos; for which recent Lao records are more substantial than those from anywhere else in a species's range; or have limited geographical range of which Laos is a substantial part. A revised set of key species for future use in Laos is given in Appendix 2.