Primary environmental health is a strategy of environmental action formulated by the Pan American Health Organization to articulate the practices of environmental and health attention, considering social, intersectorial, interdisciplinary, and sustainable context. This study seeks to identify the understanding of nurses of basic health net on the expression primary environmental care and the principles of the strategy that are being developed in the work of these professionals. This is a quantitative, cross-sectional study structured interviews were carried out with 36 nurses on the basic health assistance in the municipalities of Rio Grande and São José do Norte, in the state of Rio Grande do Sul. The results led to the fact that the understanding on primary environmental care is visualized through activities of sickness prevention and prevention on aggravation. The commitment of the professional as a citizen, in assuring each person to have access to a healthy environment is the principle of the primary environmental care that nurses identified as being developed in the basic health care net. The ways nurses developed their work in the health care net are close to the theme of primary environmental care, showing the guiding elements, even if they are not known.