Mountain areas are of great importance to biodiversity conservation. Also, they have long been reputed as the last remnants of virgin, unspoiled nature. In this paper, we assess the degree of human impact on mountain ecosystems through the Human Influence Index (HII), using it as a proxy to estimate the degree of threat to mountain biodiversity. We also measured how well the least human-influenced mountain areas are protected (HII ≤ 10). Our results show that still-large proportions of mountain areas are under low or moderate human influence, as assessed by the HII. However, these results should be considered carefully, because the HII does not include some important human-made influences affecting mountain ecosystems globally, such as climate change. Finally, 34.7% of the mountain area under low human influence (HII ≤ 10) is currently covered by nationally designated protected areas.