This article analyses selected case law of the European Court of Human Rights (ECHR) as well as Polish case law in the subject matter specified in the title, i.e. the monitoring of Internet use by employees in the workplace. The author has selected the research subject based on the own observations on the existence of nuances and divergences in the ECHR’s case law in this field, as well as a growing importance of this matter in the context of increasing employees’ online activity at work. The study is based on such research methods as content analysis, comparative legal methodology and the formal-dogmatic approach.