Sarcoidosis is a multi-systemic disorder, meaning that it can involve any organ in the body and that its clinical presentation is highly variable. In 90% of all sarcoidosis cases the lungs are affected. It is difficult to give a concise definition of sarcoidosis due to the fact that its exact cause is still unknown. Consequently, diagnosing the disease is also rather difficult. Up till now, sarcoidosis is generally diagnosed by using general clinical methods to evaluate the status of the lung including a chest X-ray, lung biopsy and bronchoalveolar lavage (BAL). However, some of these methods are considered to be rather invasive and, even more important, non-conclusive. Therefore, the current study has been designed to evaluate the use of a new technique, called SELDI-TOF mass spectrophotometry, for the diagnosis of sarcoidosis. This technique enables the analysis of all enzymes present in the blood of sarcoidosis patients which may hopefully lead to creating a disease-specific protein-profile that may facilitate the recognition of sarcoidosis. Moreover, these results will be compared with other currently used laboratory parameters.