The authors deal with the issue of determining the appropriate legal bases for the processing of personal data by employee representatives. The main objective of this paper is to assess the use of the relatively new European legislation on the protection of personal data in the specific environment of individual and collective employment relationships on the part of employee representatives. In the paper, the authors try to confirm that employee representatives in addition to the consent of a natural person concerned are entitled to act in line with another legal basis - the public interest (or fulfillment of legal obligations) given their position in the implementation of individual and collective labor relations. According to the authors, the choice of a specific legal basis will be based on the assumption that the employee representatives process personal data of the natural persons concerned, e.g. for the purposes of exercising the competencies granted by the relevant labor law regulations or for the purposes of managing internal relations of employee representatives (trade union membership as a personal data of a special category, fulfillment of rights arising from the trade union membership by a natural person). The authors substantiate their claims with relevant references to the practice, international legal documents and subsequently emphasize their use within specific labor law institutes.