The aims of this survey is to investigate about topics of library cooperation in NILDE network among university and higher education institutions libraries (geographic countries of ILL-DD exchanges, document delivery methods, payment and processing times, requested items type) and to collect feedback useful to promote NILDE internationalization and to improve NILDE services. The survey target is over 900 NILDE libraries in Italy and abroad (Spanish REBIUN libraries and other foreign libraries participating in NILDE network) and the purpose is a systematic investigation of ILL-DD activities in libraries members of NILDE network. Reflections, conclusions and suggestions were drawn from the data obtained.