The methods for laboratory diagnosis of rheumatic diseases are subdivided into 10 groups according to their informative value. The following aspects are taken into consideration: general diagnosis of inflammation, infective processes with hemolytic streptococci and staphylococci, streptococcal agglutinations, rheumatoid factor tests in the strictest sense, detection of autoantibodies, the HLA-system, investigations in metabolic diseases and generalized skeletal diseases, bacteriological and serological investigations in joint infections and tests in symptomatic diseases of joints and muscles. In the evaluation of the individual methods and the discussion of their application in various types of disease, the following provisional diagnoses are gone into: streptococcal rheumatism, rheumatoid arthritis, monarthritis, ankylosing spondylitis, Reiter's syndrome and psoriatic arthritis, myositis and polymyositis.