This research aims at analyzing the knowledge and use of the conjunctive connectors as, although, but and because by deaf people, considering LIBRAS - Brazilian sign language - as their first language, in a Portuguese as a second language (L2) teaching-learning approach . Based on the functionalism model and on the argumentative semantics, it starts testing adolescent and adult deaf informants, students of some private schools in Rio de Janeiro, from the the 5th to the 8th grade, who demonstrate their performance in the usage of these connectors in the written form of the Portuguese language. Through the tests results we could verify that their competence in the use of conjunctive connectors elements relates to linguistic facts, such as lexical, syntactic and textual-semantic issues, and to extralinguistic facts, such as school level, deafness level, age, proficiency level at LIBRAS and Portuguese language, and also to the kind of test applied. It has been noticed that the informants who know LIBRAS have a better performance in Portuguese. Eventually, it is highlighted the importance of reflections on this theme to researches on the Portuguese teaching-learning process as a second language for the deaf, as well as to the implementation of actions concerning changes in the current Brazilian methodologies.