Identifica, no ordenamento jurídico pátrio, a proteção da família matrimonializada e de seu patrimônio quando o sossego e a estabilidade familiar se vêem ameaçados pela existência do concubinato adulterino. A pesquisa inicia-se com um breve apanhado sobre as origens da família e do concubinato e se estende até os dias atuais, explicitando a evolução do posicionamento tanto social quanto jurídico no que concerne à existência do concubinato. Analisa a doutrina, a legislação,a jurisprudência e os apectos constitucionais do tema.; The central objective of this work is to identify in the national laws the protection of matrimony family and its patrimony when the family calmness and stability is being threatened by the existence of the adulterine concubinage. The research is initiated with a brief study on the origins of the family and concubinage and extends until the current days clarifying the evolution of both legal and social views concerning the existence of concubinage. The paper makes the necessary clarifications of the definitions and concepts used along the work and sets the relevant points for the development of the research. For this purpose, doctrinal, legislative, constitutional and mainly jurisprudential research has been used. This research is concluded with the presentation of results, highlighting the patrimonial guardianship of the family and expliciting the current legal positioning.