This chapter examines the implications of blockchain technology on the processing of personal data and its compliance with the general data protection regulation (GDPR) within the European Union. While the internet has revolutionized communication and database systems, it has also posed challenges to legally process personal data. However, the introduction of blockchain technology, with its cryptographic features and decentralized peer-to-peer ledger system, raises questions about the applicability of the GDPR. This chapter analyzes personal data processed in public blockchains, including the right to erasure. Additionally, the chapter explores the complexities of establishing accountability within distributed ledger technology, considering the innovative nature of blockchain and the traditional database framework upon which the GDPR was constructed. By examining the relationship between blockchain participants and fundamental data protection rights, this research aims to shed light on the intersection of blockchain technology and personal data protection