In parallel to the devolution of authority from member nations to the EU, the lobbying actions of various entities towards EU institutions have expanded over time. A variety of organisations coordinates lobbying efforts on behalf of EU institutions. The aim of this research is to investigate the impact of a candidate country's interest groups' lobbying efforts by focusing on Turkey as a case.Due to the length of the EU membership process, which has exceeded 20 years, Turkey is regarded as an exceptional case. This study examines the lobbying actions of four economic and two political bodies in Turkey between 1999 and 2021, based on a typological description of two sorts of groupings. In terms of research method, a two-stage approach was adopted by using qualitative and quantitative tools together. In the first stage, written documents were analysed to determine the institutions’ general attitudes towards the EU accession process and the topics they focus on. The documents in question includes periodic activity reports, thematic reports, press releases, statements of institution representatives for non-governmental organizations and party programs, election manifestos, statements of party leaders or representatives, and parliamentary minutes for political parties. In addition, the news in the national media about the activities of the institutions was examined through an extensive media scan. Following this, in the second stage, semi-structured questionnaires were prepared for all institutions and answers were sought in in-depth interviews with EU representatives of the institutions examined, EU decision makers who are the addressees of the lobbying activities, and relevant experts on lobbying in the EU. According to the findings of the research, the study suggests that variations in Turkey-EU relations have a detrimental impact on the lobbying actions of these entities. However, the lobbying actions of the entities listed below are less influenced by these changes. These are the groups that focus on their particular field of operations at the technical level rather than the Turkish accession process and create deeper relationships with transnational umbrella organizations. The statistics imply that non-governmental organizations are more effective than political parties in EU lobbying actions.