The high N inputs to agricultural systems in many regions in 27 member states of the European Union (EU-27) result in N leaching to groundwater and surface water and emissions of ammonia (NH(3)), nitrous oxide (N(2)O), nitric oxide (NO), and dinitrogen (N(2)) to the atmosphere. Measures taken to decreasing these emissions often focus at one specific pollutant, but may have both antagonistic and synergistic effects on other N emissions. The model MITERRA-EUROPE was developed to assess the effects and interactions of policies and measures in agriculture on N losses and P balances at a regional level in EU-27. MITERRA-EUROPE is partly based on the existing models CAPRI and GAINS, supplemented with a N leaching module and a module with sets of measures. Calculations for the year 2000 show that denitrification is the largest N loss pathway in European agriculture (on average 44 kg N ha(-1) agricultural land), followed by NH(3) volatilization (17 kg N ha(-1)), N leaching (16 kg N ha(-1)) and emissions of N(2)O (2 kg N ha(-1)) and NO(X) (2 kg N ha(-1)). However, losses between regions in the EU-27 vary strongly. Some of the measures implemented to abate NH(3) emission may increase N(2)O emissions and N leaching. Balanced N fertilization has the potential of creating synergistic effects by simultaneously decreasing N leaching and NH(3) and N(2)O emissions. MITERRA-EUROPE is the first model that quantitatively assesses the possible synergistic and antagonistic effects of N emission abatement measures in a uniform way in EU-27.