Resumo: This study is the result of a broader study developed within a research that aims at contributing to the development of sustainable tourism and environmental education in the Montesinho Natural Park and Douro International Natural Park. These aspects are considered of great relevance, because in this way a contribution will be made for the implementation of development models in sustainable tourism and environmental education as well as for the improvement of the local inhabitants of the Montesinho Natural Park and Douro International Natural Park.It is believed that natural spaces allow a more sustainable tourist use in addition to performing an important role in the quality of life of people. In this context, the problematic of sustainable tourism in protected natural spaces is discussed, and some international documents related to this issue are considered. Then, an analysis of the number of visitors to the Montesinho Natural Park and Douro International Natural Park is made.
