The submitted paper reviews contemporary knowledge on the clinical impact of assessment of HLA-complex antigens in systemic rheumatic diseases. The authors explain the term "relative risk" and its practical importance. As to antigens of the HLA-complex class I, attention was paid in particular to the importance of HLA B 27 in ankylosing spondylitis, other spondylarthropathies and reactive arthritis; in this part the review is supplemented by results of the authors' own research. As to antigens of the HLA-complex class II, attention was paid to the sub-area DR in rheumatoid arthritis and other diffuse affections of connective tissue. The advance in knowledge of the clinical impact of investigations of selected HLA-complex antigens in systemic rheumatic diseases is that in many instances it reveals an association not only at the level of the nosological unit but frequently also sub-unit with prognostically important clinical and biochemical manifestations, a typical autoantibody profile and sometimes also with the risk of a greater organ toxicity of drugs.

Keywords: HLA Antigens /analysis/; Humans; Rheumatic Diseases /immunology/