There exists a strong link between mountain regions and biodiversity. These regions represent the most important source of regional and global ecosystems forming the core elements of environmental and sustainable development policies. Mountains operate as true refuge for endemic species but are affected by uncontrolled human actions, while alpine meadows are exposed to losses of traditional pasture practices. Mountains can be analyzed from the economic, ecological, environmental, social, cultural viewpoints and their multidisciplinary nature is acknowledged both in the academic milieu and by decision makers involved in territorial development policy. The negative impact of economic activities in mountain regions is becoming more visible, therefore, necessitating a sustainable approach to preserve the biodiversity and habitat in order to salvage the fragile ecological balance. The present paper gives an overview of the relationship between biodiversity and sustainability within mountain regions and its implications on the economic and social development process. By interpreting the finding of previous research and studies, the article presents the current knowledge of mountain biodiversity in Europe and Romania and its relationship with sustainable development process.