The Frente Parlamentar Nacionalista (FPN) [National Parliamentary Front] and the Ação Democrática Parlamentar (ADP) [Parliamentary Democratic Action] were political groups which led the debate in the Nacional Congress in the beginning of the 1960s. The former was organized based on an anti-imperialist agenda; the latter, named itself as anticommunist. This paper seeks to reconstitute the main political events of that time from their point of view. Through the analysis of the speeches in plenary of the members of the two parliamentary fronts, of their presence in the permanent committees and in the parliamentary committees of inquiry (PCIs), in the legislative production and their behavior in roll-call votes, it is aimed to point out that the two groups enhanced the ideological radicalization and the political polarization of the House of Representatives. Discussed here are also the organizational structures of the two parliamentary fronts, which appeared to be bureaucratic with established positions and functions for their members. In the roll-call votes regarding the agrarian reform and the regulation of the foreign capital, it is concluded that FPN was orienting the voting in plenary and the ADP was essential to some polls concerning the thematic of the parliamentarianism. Both FPN and ADP were present at the Board of Directors and in strategic permanent committees; in the legislative production, FPN seemed to influence its members in the elaboration of projects of its own interest. In the participation in PCIs, ADP had a higher performance, both in its elaboration and functioning. Defending dichotomous projects in a context of intense radicalization, the parliamentary fronts were fundamental to strengthen the political crisis of the 1960s.