Public sector bodies are increasingly relying on the Internet. On this channel, indispensable information is transmitted to the public and a wide range of services is already available. Therefore, the usability, accessibility, and the security of these websites are very important. Accessibility is particularly crucial for persons with disabilities. The accessibility of public service websites is regulated by a number of laws; among others, the directive "on the accessibility of the websites and mobile applications of public sector bodies" adopted by the European Parliament in 2016. This obliges all European Union member states to make all public sector websites and mobile applications accessible by 23 September 2021. In practice, this means that websites must fulfil the level AA recommendations in WCAG 2.1. In our study, a website assessment method is developed by comparing different analytical tools. With this method, we analysed how Hungarian websites of public sector bodies fulfil the requirements of the directive. We have also investigated how well they comply with usability and security guidelines. The results showed that none of the 25 websites of the examined Hungarian public sector bodies could completely fulfil the recommendations of the Web Content Accessibility Guidelines (WCAG) and that half of the websites had only the lowest level of compliance in usability tests. From the security point of view, almost half of the websites use outdated server versions and programming language, which is very critical. We have proposed several suggestions to address the major problems, so website developers and administrators can improve the accessibility, usability, and security aspects of these websites.