There have been several new insights into the cause and treatment of sarcoidosis. Studies of genetic variation have shown that specific genetic polymorphisms are associated with increased risk of disease or affect disease presentation. These polymorphisms include variation of MHC and cytokines such as tumour necrosis factor (TNF). Not all investigators have come to the same conclusion, suggesting an interaction of various factors, including the patient's ethnic origin. Treatment of sarcoidosis varies considerably. Patients with symptomatic disease for more than 2–5 years have been of particular interest. Corticosteroids remain the standard of care in such cases, but immunosuppressive drugs have proved steroid-sparing in many patients. New agents, including pentoxifylline, thalidomide, and infliximab have proved useful in selected cases. The effectiveness of these agents seems to lie in their ability to block TNF, especially in the treatment of chronic disease.