The advent of Internet has deeply changed the way we live. More than just moving our daily reading, shopping and entertaining to an on line environment, the Internet has been regarded as the catalyst for companies to reconsider their business modes and processes. A new business model: e-business, was then born. The size of this new model is remarkable and it keeps growing nowadays. The extranet, a level of connection of the Internet, is a relatively young business to business (B2B) technology. It has gained a lot of attention from both managers and researchers, since it possesses plenty of potential benefits. This thesis studies the particular case of the extranet applied to the supply activities occurring between the buyer and its established suppliers. The objectives, goals and outcomes that companies have when implementing the extranet are discussed as well as the factors that influence the implementation process. A multi-case study strategy was chosen where three multinational manufacturers were selected. In order to get the necessary data, people working in the purchasing areas of these companies were interviewed. As a result, we obtained that the extranet brings benefits to organizations, merely in terms of money savings. Furthermore, it was found that not all of the obtained outcomes were preset. As a final point, “people” was found to be a fundamental factor for the successful implementation of the extranet as well as arduous to deal with.