Ecological security, at the local and global levels, is becoming one of the priority tasks of modern civilization. Contemporary world is facing many challenges,  among which environmental problems have occupied most of the world's attention. Environmental protection is an unavoidable factor of internal stability and security of a country, so it is necessary to discover which factors threaten the environment and have an impact on ecological security. Mining activities have adverse effects on ecological security which, as a consequence, raises the necessity for continuous environmental monitoring in these areas. One of these areas is the municipality of Majdanpek in Serbia, where the principal part of inhabitants is employed in mining. This paper presents a case study on ecological security in the municipality of Majdanpek, through a subjective perception of the inhabitants’ safety and vulnerability in terms of four key indicators: water, air, soil and biodiversity.