Any condition that causes inflammation or swelling of the muscles is called myositis. It has various causes, which include inflammatory conditions, injury, infection and immune disorders. Most of the causes of myositis are autoimmune in nature wherein the body attacks its own muscle tissues. Inflammatory conditions such as dermatomyositis, polymyositis, and inclusion body myositis cause severe myositis. Lupus, scleroderma, rheumatoid arthritis are some of the milder forms of myositis. Common cold, flu viruses, and human immunodeficiency virus (HIV) are some viruses that may cause myositis. Its treatment depends on the underlying cause. Myositis caused due to inflammatory conditions requires treatment with drugs such as prednisone, azathioprine and methotrexate that suppress the immune system. This book is compiled in such a manner that it will provide an in-depth knowledge about the types, diagnosis and treatment of myositis. The readers would gain knowledge that would broaden their perspective about this medical condition. The book is appropriate for students seeking detailed information on myositis as well as for experts.