Public institutions are beginning to realise that they must shift their management towards sustainability. Thus, public sector, including defence services, environmental performance evaluation is a growing reality. The main objective of this research was to assess the environmental pressures and impacts profile of the Portuguese defence sector. A questionnaire survey was conducted involving all Portuguese military units that have a person in charge of environmental issues. Respondents generally reported that the majority of their activities have few serious environmental problems. These results could show the respondents' general perception of the increasing implementation of environmental management practices in military units and probably some lack of knowledge, but also a standard based on compliance with regulations. Many environmental pressures in the Portuguese military are related to primary environmental problems, such as water supply, wastewater and solid waste, showing that the integration of environmental awareness and practices into the Portuguese military is quite new.