This paper studies the configuration of institutional practices and their historical determinations at Hospital São Vicente de Paulo-HSVP reference hospital in the Federal District for psychiatric treatment, from 1985 to 2002. A qualitative research was chosen, using a historical-structural approach and case study technique. The authors elected ideology as analytical category and, as empirical categories, mental health care and the psychiatric reform. The research tools used were interviews with key informants and institutional subjects (16 health professionals, 12 clients and 9 family members), analysis of documents and interactive observation. The authors concluded that, from 1999 onwards, mental health practices at HSVP have suffered a retraction in regards to the Psychiatric Reform, as the hospital has implemented its policy of desinstitulization, but at the same time has submitted its clientele, patients and families to a situation characterized by poor medical assistance and social exclusion.