Environmental radioactivity monitoring in Portugal is a nationwide programme that consists of two complementary (sparse and dense) sampling networks established following the EURATOM recommendations [2000/473/EURATOM-Commission Recommendation of 8 June 2000, Official Journal of the European Commission, no. 191, 27 June 2000]. This paper describes the aim of the monitoring programme, how it was implemented, the sampling locations, the type of samples, the analytical and measurement methods and the quality control programmes. Some representative results are also discussed. Based on the monitoring data it can be concluded that the Portuguese population has not been exposed to radioactivity levels that require any radiological protection measures.