The work investigates the debate regarding sexual orientation in the 1987-1988 National Constituent Assembly (ANC). One of the objectives of the research is to describe the discussions on the theme, with special attention to the mentions of lesbian, gay, bisexual, trans, intersex and other gender and sexuality dissidents (LGBTI+). The second objective of the thesis is to conduct a critical analysis of the discourses, with attention to the productive power of discourse. The research adopted as a theoretical framework the notion of gender performativity, developed by Judith Butler, and its critical outcomes concerning the process of subject construction. The main research technique employed was document analysis, which helped in obtaining primary data from the proceedings of the ANC and the documents made available in Fundo João Antônio Mascarenhas of the Edgard Leuenroth Archive. The methods guiding the examination are Foucauldian discourse analysis and grounded theory. The results show how was the articulation of the political advocacy coordinated by Triângulo Rosa in the Constituent, its limitations in relation to the representation of the social group, and the processes of hierarchization of identities that constitute the base of the LGBTI+ Movement, with particular exclusion of transvestites and transsexuals. In addition, the work demonstrated the contemporary persistence of certain discursive formations, especially through the opposition of congressmen linked to religious sectors to the demands of LGBTI+ people; and found empirical evidence that protection against discrimination based on sexual orientation is covered by the general prohibition provided for in the current Constitution.