Abstract This article analyzes the development of primary care (PHC) within the Unified Health System (SUS) in large Brazilian cities. The decision to adopt a policy of PHC represented an incremental reform of the health system through the Family Health Strategy (FHS). The methodological approach of the article uses cross-sectional data grouped around two years (2008 and 2012) to evaluate the development of PHC in the cities. The article demonstrates that the funding of the health sector expanded in all Brazilian cities, regardless of population size, in the early 2000s. The growth of municipal health expenditure in terms of public health actions and services helps to explain the high level of provision of family health teams that was observed mainly in small cities in the early 2000s. The analysis of health provision also shows that the provision of family health teams remained relatively stable during the period that was analyzed in most municipalities of medium and large population size, and also in the metropolises. The development of PHC during the studied period reveals that the risk of the over-supply of health services associated with the decentralization of the health sector did not occur in Brazil. The large cities and metropolises underwent a significant, but unequal, expansion of PHC.