A market study is presented, concerning fiber optic biosensors which have been developed in Europe. The main aspects discussed in the study are principal applications, a sketch of the European companies involved in research and production, their success, and future market trends. The key areas in which fiber optic biosensors are highly competitive with conventional devices are pH and blood-gas monitoring and immunoassay. In addition to these leading applications, there is also interest for many applications in monitoring temperature, pressure, and blood flow. Other sensors of interest are more specifically addressed to particular aspects of certain diagnoses or therapies: for example, for monitoring glucose, bile, the light level in tissues, kidney stones, or parameters related to metabolism.