After the designation of twelve Special Protection Areas (SPAs) Luxembourg was asked by the European Commission to evaluate this network by analysing its contribution to the viability of the 64 bird species for which Luxembourg has to select sites. For 34 species which are good or very good covered by the network in a qualitative way the contribution of the designated SPAs was evaluated focusing on the method of site selection. For these species it was concluded that the SPAs and six selected Important Bird Areas (IBAs) include all important sites in Luxembourg. There is no need for selection and designation of additional SPAs to fulfill the obligations of the Birds Directive. For 30 species which are not or badly covered by the SPA network the model LARCH was used to analyse the spatial conditions of the network providing long term protection in terms of viable populations. The analyses show only a few species which are viable within the existing network. For most species additional sites are needed to reach a sustainable network. Priority areas where additional sites can be found are also analysed. Because additional sites can contribute to the viability of different species priority areas were analysed showing their added value to the viability of a combination of species using the same habitat.