This article analyzes the trajectory of national health policy in Brazil from 1990 to 2016 and explores the policy's contradictions and conditioning factors during the same period. Continuities and changes were seen in the policy's context, process, and content in five distinct moments. The analysis of the policy's conditioning factors showed that the Constitutional framework, institutional arrangements, and action by health sector stakeholders were central to the expansion of public programs and services, providing the material foundations and expanding the basis of support for the Brazilian Unified National Health System at the health sector level. However, historical and structural limitations, institutional legacies, and the dispute between projects for the sector have influenced national health policy. Interaction between these conditioning factors explains the policy's contradictions during the period, for example with regard to health's position in the national development model and social security system and the financing and public-private relations in health. Expansion of public services occurred simultaneously with the strengthening of private segments. Dynamic health markets that compete for resources from government and families, limit the possibility of consolidating a universal health system, and reiterate social stratification and inequalities in health.