The present dissertation examines the balance between the protection of employees’ personal data and legitimate Greek business activity. It is well-known that businesses tend to supervise their employees’ activities to ensure their proper performance. While it is true that businesses may have a legitimate purpose, employees' privacy should be protected, as well. The detention and process of employees’ data are regulated not only by European but also by Greek personal data law. The balance between the proper functioning of a business and the protection of sensitive data of employees is desirable, but many times seems to be impractical. As far as the methodology of the present dissertation is concerned, we adopt the literature review model, namely: (a) literature search and screening; (b) data extraction and analysis; and (c) writing the literature review. The importance of the present dissertation is great, given the fact that a balance needs to be struck between, on the one hand, the Greek businesses' need to process personal data and on the other hand, the privacy of their employees.