Introduction: Sugary drinks taxation is among a set of recommended public policies to tackle obesity and diet-related non-communicable diseases. However, it faces strong opposition from the industry, which uses corporate political activity (CPA) strategies and practices to prevent it. Objective: To assess whether CPA of the sugary drinks and their inputs industriesespecially electoral campaign financing and lobbyinghave influenced decision-making on sugary drinks taxation in the 55 th Congress of the Brazilian legislature (2015)(2016)(2017)(2018)(2019). Methods: Data on campaign contributions from the sector to congressional candidates (Federal Senate in 2010 and Chamber of Deputies in 2014, available from the Superior Electoral Court, were assessed. Contributions were described according to variables related to sociodemographics, region, and political party. Generalized linear model analysis with negative binomial regression was used to assess the effect of the contributions on the chances of election. Legislative proposals related to sugary drinks taxation considered during the 55 th Congress were identified. Four of them were selected for a case study to explain their approval in the Federal Senate, using the Qualitative Comparative Analysis, and their subsequent rejection in the Chamber of Deputies. Results: Fifty-six corporate groups that produce sugary drinks and 62 that produce their inputs (sugar and fruit concentrates) contributed to the campaigns. In 2010, contributions from input industries prevailed while in 2014 those from sugary drinks industries did. Participation from corporate groups associated to Abir, Unica, and CitrusBR also prevailed. Contributions benefited 96 candidates to the Federal Senate and 585 to the Chamber of Deputies and helped elect 48 Senators and 237 Federal Deputies. Four Legislative Decree bills aimed at keeping tax benefits to soda industries which operate in the Manaus Free Trade Zone (MFTZ) were selected for the case study. The interests of major sugary drink industries prevailed in the Federal Senate, where the favorable votes of the Senators were explained by the following conditions, isolated or combined: representing a State with free trade area of the MFTZ; being filiated to PSDB; having received campaign contributions from the sector; having an interest promoted by one of the Senators who supported the maintenance of the tax benefits to soda industries in the MFTZ; representing a State from the North or Northeast; defending tax benefits for their own region; having being elected in 2010. In the Chamber of Deputies, rejection of the bills was determined by the absence of political articulation of the representatives of Amazonas State and the deliberation in the Finance and Taxation Committee, where there was a group of members who were favorable to the interests of soda industries based in other States. Members of both legislative Houses showed little concern regarding the public health issue involved. Conclusion: The actions taken by the private sector to maintain th...