This undergraduate thesis on the topic of "Data Protection in Public Administration" initially presented the difference between the definitions of data and information and the DIKW hierarchy of data, information, knowledge, and wisdom. The next chapter dealt with the right to privacy and its protection, also mentioning "sharenting" - a term that describes the situation where parents share various information about their own children on the Internet. Following this, the focus was on information systems and security, where the information systems of the judicial bodies of the Republic of Croatia are mentioned, the importance of information security is explained, and the e-Citizens project is described in more detail. The principles of information security are also mentioned, with the CIA Triad being particularly noteworthy. Furthermore, the paper discusses various dangerous types of attacks on systems and the methods and means of protection against them. Perhaps the most important chapter is the last one, which discusses the GDPR and its undeniable importance for data protection.