Foucault and Freud. The building of subject in the marc of the relationships of power carry out by discourse from the language. Resumen El articulo presenta una reflexion sobre la forma en que el conocimiento circula y funciona, sus relaciones con el poder, y particularmente su efecto sobre el proceso de constitucion del sujeto, partiendo de Freud para conectar con Foucault, invitando a comprender el papel de nuestro saber en medio de las relaciones de poder de las que hacemos parte en la dinamica cotidiana de nuestras vidas como ciudadanos y como psicologos. Palabras clave: lenguaje, discurso, relaciones de poder, sujeto. Abstract The article presents a reflection on the way in which knowledge flows and works, its relations with the power, and particularly their effect on the process of Constitution of the subject, from Freud to connect with Foucault, inviting to understand the role of our knowledge in the midst of the power relations of which we are part in the dynamics of everyday of our lives as citizens and as psychologists. Keywords: language, discourse, power relationships, subjet.