The main objective of this exploratory and descriptive study was to acknowledge the instruments used to assess health needs of the population in the Family Health Strategy. Two districts of Sao Paulo Municipality, Brazil, were taken as the scenario. The theoretical and methodological basis was the Theory of Praxical Intervention in Collective Health. Data were collected in Heath Care Units, with Family Health teams' members. The results showed the inexistence of specific instruments to assess health needs. The discussion addresses the three contractions identified: the structural polarity in the conceptualization of health needs in the Brazilian Unified Health Care System, the principle of integrality postulated by this System and the possibility of its implementation by the health care teams, and also the theory-practice antinomy in their labor process. The conclusion is that these contradictions must be overcome in order to redirect policies and practices towards health needs assessment.
Health services needs and demand; Public health; Family health; Community health nursing