E-health has experienced a dynamic development across the European Union in the recent years and enjoys support from the European Commission that seeks to achieve interoperability of national healthcare systems in order to facilitate free movement. Differences that can be observed between the member states in legal regulations, cultural approaches and technological solutions may hinder this process. This study compares the legal standing of e-health in Denmark, Poland, Spain and the UK, along with key legal acts and their implications. The academic literature review along with an analysis of materials found through the desk study research (reports, legal acts, press articles, governmental web pages and so on) was performed in order to identify aspects relevant to e-health interoperability. The approach to legal regulation of e-health substantially differs by country. So do the procedures that they have developed regarding the requirement for patient's consent for the processing of their data, their rights to access to the medical data, to change the data, data confidentiality and types of electronic health records. The principles governing the assignment of responsibility for data protection are also different. These legal and technological differences must be reconciled if interoperability of European national e-health systems is to be achieved. Copyright © 2016 John Wiley & Sons, Ltd.