Current research in biology heavily depends on the availability and efficient use of information. In order to build new knowledge, various sources of biological data must often be combined. Semantic Web technologies, which provide a common framework allowing data to be shared and reused between applications, can be applied to the management of disseminated biological data. However, due to some specificities of biological data, applying these technologies to life science is a real challenge. This chapter shows that current Semantic Web technologies start to become mature and can be used to develop large applications. However, in order to get the best from these technologies, improvements are needed both at the level of tool performance and knowledge modeling.