Abstract: Abstract Wild Bactrian camels Camelus bactrianus ferus are endangered. Surveys over the past several decades suggest a marked decline in camel numbers and reproductive success. However, most surveys were made using methods that precluded rigorous population estimation. The need for more accurate surveys resulted in an aerial survey of known and suspected camel habitat in Mongolia during March 1997. We estimated density, group density and population size of large mammals in south-western Mongolia using the interactive computer program DISTANCE. We recorded sufficient data for population modelling of wild Bactrian camels, goitred gazelles Gazella subgutturosa, Asian wild asses Equus hemionus and argali sheep Ovis ammon. We observed 277 camels in 27 groups (mean group size = 10.269 +- 2.38 SE camels: group). Modelling yielded a population estimate of 198 +- 802 SE camels in the survey area. Population modelling for other ungulates yielded estimates of 6046 +- 1398 SE goitred gazelles, 1674 +- 506 SE Asian wild asses and 909 +- 303 SE argalis. Discrepancies between population estimates of ungulates in our survey and previous surveys are discussed with regard to methods used and robustness of results obtained. We also discuss conservation implications for wild Bactrian camels and other Mongolian ungulates.