In the diploma thesis on Digitalised Incunabula in the Croatian National and University Library in Zagreb, it is shown how libraries have recognised the important role of digitalising the material with the purpose of enabling easy access as well as preventing its decay, since one of the most important roles of libraries is preservation and restauration of resources. National and University Library in Zagreb, also recognizing the importance of preservation of this fragile and unique materials, started with digitalization processes. The Croatian Incunabula have been of vital importance, especially as testimonies of cultural aspiration and creative effort of one little nation, along with documenting our long lasting relations to great centres of European culture. The Incunabula Croatica collection has been an integral component of the Digital Resources Collection created and preserved by National and University Library in Zagreb. It is the result of the Incunabula Croatica Project which was implemented as a part of the Croatian Cultural Heritage Project (2010 – 2011). The goal of the project itself was digitalisation of the Croatian incunabula. This diploma thesis presents research and final data on the exact number of incunabula digitalisation projects implemented by the National and University Library in Zagreb and the number of digitalised incunabula. Furthermore, it explains whether there had been any encouragement of digitalization in other institutions, as well as organizing a comprehensive digital resources collection along with cooperating and purchasing abroad. Finally, the thesis proves success of the project despite the inevitability of the financial insufficiency. The aim of this diploma thesis is to raise awareness of the importance of digital environment as a platform for research, gaining and exchanging experiences, attitudes and personal values, along with enabling easy access to important documents of Croatian national and cultural identity, to everyone interested in this valuable material.