RESUMO
The study aims to examine nurses' understanding of the principles of the Unified Health System. universality, equity and integrality. This is a descriptive study conducted from August to September, 2008, through semi-structured interviews with 26 nurses of the basic units of Health fom Fortaleza, Ceará, Brazil The technique o f content analysis was used toorganize the data. The results show that nurses perceive universality as a universal access for all users of health services; equity as an equal attendance of the population, guaranteeing special attention to the poor; and integrality of care as the provision of services at all three levels of care. The conclusion shows that the practitioners' conception of these principles are similar to those presented in the Federal Constitution. This represents an important element for the implementation and strengthening of the model of health care in Brazil.
