Enhancing data subjects’ rights in order to increase control over personal data is doubtless GDPR’s priority. Though, the protection of personal data and human rights does not rely only on the legal framework, but also on data subjects’ knowledge regarding their right to data protection. This paper building upon a research having explored a group of Greek data subjects’ extent of knowledge about the rights GDPR guarantees which revealed that there is not sufficient knowledge for all the rights investigated, aims to explore factors that affect the extent of rights knowledge focusing on information sources and demographic variables. The results show that rights knowledge extent is not that much affected by respondents’ demographic characteristics, while on the contrary the sources of information on GDPR impact more. This generates the need for more awareness programs, national campaigns and educational interventions on GDPR targeted to the public, in order to prevent the emergence of a new form of inequality between data subjects as a result of rights’ knowledge gap.