The processing of the personal data of the members of the Catholic Church is essential for the attainment of objectives associated with the administration of Church affairs. The right to process data – despite some restrictions imposed on the interference of the Inspector General for Personal Data Protection – is linked with the obligation to diligently and properly protect personal data. The article presents the ways of protecting personal data processing by the Catholic Church in Poland which are prescribed principally by the Code of Canon Law of 1983, the Act on the Protection of Personal Data and The Guidelines on Personal Data Protection in the Activity of the Catholic Church in Poland.