This thesis is dedicated to the study of lobbying, especially from the perspective of regulating the activity in Brazil. For this purpose, it follows an analytical line that seeks to move towards the confluence of law and political science. From the very beginning, the intention is to delimit the object of analysis by delving into the origins and meanings attributed to lobbying, as well as the figure of the professional lobbyist and its field of activity, which the research chooses to limit to the National Congress. From there, the focus falls on the behaviors related to the practice (involving interest representatives and public agents). In Brazil, the resulting relationships are generally located in a zone of ethical and normative penumbra, persistently associated by public opinion with the idea of corruption. Not surprisingly, one of the main arguments in favor of specific regulations on lobbying is to clarify its limits. This suggests a gain in legal certainty for those involved and a bonus of transparency for the purposes of social control. On the other hand, there are voices that argue for a broader scope of regulation, particularly to address the unequal access of groups involved in lobbying. Given the significant inequalities that afflict the country, this problem becomes relevant. Therefore, this work proposes a more pragmatic reading, aware of the Brazilian context. Methodologically, it is grounded on interdisciplinarity and comparativism, as well as attentive to possible contributions from public choice theory for a critical assessment of the topic. With these guidelines established, the thesis moves on to an exploratory approach to the regulatory modalities in place, which is done considering the experience of countries that have already addressed the issue, in order to identify contributions to the debate at the national level. Finally, the investigation focuses on the circumstances of lobbying in Brazil. Ultimately, it is expected to provide a diagnosis of the impasses and efforts to regulate the matter in the National Congress