Various preparations of Tripterygium wilfordii Hook F (TwHF) have been used in the treatment of a number of autoimmune and inflammatory diseases since the 1960s. Accumulated data from the clinical trials suggest efficacy of this treatment in a number of rheumatic diseases, including rheumatoid arthritis and systemic lupus erythematosus. Studies on the relationship of the chemical components of TwHF and its immunosuppressive and anti-inflammatory effects suggest that diterpenoid compounds with epoxide groups account for the therapeutic effects of this herbal remedy. This herbal remedy is therefore a unique and powerful alternative therapy for autoimmune and inflammatory diseases.