In late spring 2005, we surveyed Mongolian gazelle (Procapra gutturosa) populations in a 275,000-km2 portion the eastern steppe of Mongolia to estimate their population size and assess their distribution with respect to forage and human households. We estimated a total population of 1.126 million (95% CI, 843,000–1,500,000), and found that gazelle distribution could be accurately predicted by a Normalized Difference Vegetation Index (NDVI) as an approximated measurement of vegetation productivity, and thus habitat quality. However, the presence of households had a considerable impact on gazelle density; in most regions, density was 76–98% lower than in survey blocks where no households were found. We show that in addition to large regional differences in gazelle density throughout their range, the presence of herding households had a negative impact on gazelle density in selected habitat. The conservation of ungulates that depend on the ability to make long-distance nomadic movements requires not only that access to habitat is unimpeded but also that the subtle impacts of activities associated with the presence of people need to be considered.