[en] The present document is the fifteenth report published by the Health and Safety Directorate of the Commission of the European Communities concerning ambient radioactivity and using the data collected by the stations in charge of the surveillance of the environmental radioactivity in Member States. The results are compiled and extracted from the data sent to the Commission in application of Article 36 of the Treaty of Rome instituting the European Atomic Energy Community. It is the first document in which data from Denmark, Ireland and the United Kingdom which joined the European Community on 1 January 1973 are included in addition to data from Belgium, the Federal Republic of Germany, France, Italy, Luxembourg and the Netherlands. The results presented in this report cover the years 1973 and 1974 for air deposition and surface water and the years 1972, 1973 and 1974 for milk