Although the services sector accounts for nearly 70% of employment and income in developed and developing countries alike, it is well known that the economic performance of the tertiary sector does not depend exclusively on its capacity to add value. This article will evaluate the productive structure of the sector, by considering intra- and inter-sectoral relations in three countries with different development levels: Brazil, the United Kingdom and the United States. The article uses data from the 1995, 2000 and 2005 OECD input-output tables, to calculate the field of influence of sectoral links in the purchase and sale of inputs. The results show that the services sector in Brazil is poorly integrated with the rest of the economy; but in the other two countries, the most important links are spread across the economy as a whole.