A descriptive account based on the disease of sarcoidosis has been illustrated in this book. Sarcoidosis refers to a disease which causes inflammation in various parts of the body. The reason for such inflammation still remains unknown. In general situations, whenever foreign substances enter into the body, the immune system fights back by generating immune responses. Inflammation is a part of these immune responses but it usually subsides when the foreign antigens leave the body. In sarcoidosis, abnormal clumps of granulomas tissues are formed in the body and the inflammation continues. It can affect various parts of the body but it mostly affects lungs and may also affect lymph nodes, eyes, skin and liver. The cause of sarcoidosis remains unrecognized. However, some researches indicate that it may be due to extreme sensitivity or extreme immune response to certain substances. This disease is also assumed to possess genetic components and may pass on in the family. It affects people between the age of 20 to 50 years. Also, it is more likely to affect African Americans than Caucasians and, females than males. The symptoms of this disease primarily depend on the organ involved. This book focuses on diagnosis and treatment of this mysterious disease.