The paper describes previous maps of the Diocese of Poreč and Pula and creation of a new map of the Diocese made and published after many changes and long-time research at the Faculty of Geodesy, University of Zagreb. The data collection of the general geographic content and the sacral content was the first step for the new map visualization of the Diocese. It also describes different problems for special map contents and observed shortcomings on the previous maps, and how they are solved. The research objective was the creation of the new map of the Diocese based on the collected and verified data, showing the exact borders of the Diocese and current borders of the deaneries with current seats. On the new map ( Main Map ) at a scale of 1:120 000, the parish borders with the seats and names of parishes are depicted for the first time.