Background: Tumour necrosis factor-alpha (TNF-a) plays a crucial role in sarcoidosis. In severe disease, treatment with TNF-a inhibitors may be effective. Objectives: Changes in sarcoid disease activity were assessed by fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) in patients with recalcitrant sarcoidosis treated with adalimumab. Methods: Prospective 24-week observational study. Patients continued medication with steroids and antimetabolites and received adalimumab 40 mg subcutaneously every other week. Ten patients with biopsy-proven sarcoidosis (two men) were included with a median age of 47 years (range 35-73). An FDG-PET showing uptake indicating sarcoid activity was required at inclusion and repeated at the end of the study. FDG-PET uptake was assessed by calculated standardised uptake value (SUV). Blood samples and lung function tests were performed regularly. Quality of life was assessed by the short-form health survey (SF-36) questionnaire. Results: Following treatment with adalimumab, FDG-PET uptake decreased in nine patients (P = 0.011) and increased in one patient. Maximum SUV fell from median 14.1 to 7.0 (P