The authors present a study of the incidence of HLA-DR antigens in 113 controls and in a Breton population suffering from chronic inflammatory rheumatism. They found 80 cases of rheumatoid arthritis and found a significant increase incidence of the DR4 antigen in rheumatoid arthritis (54% compared with 19.5%; pc less than 10(-4); RR = 4.8) and a decreased incidence of the DR2 antigen (12.5% compared with 35%; pc less than 10(-2); RR = 0.27). The increased incidence of DR4 does not seem to be related to the presence of rheumatoid factor. Out of the 95 cases of chronic inflammatory rheumatism treated, 33 cases of drug intolerance (cutaneous and/or renal to gold salts or D-penicillamine) were reported. The authors found a decreased incidence of the DR2 antigen in the patients who presented a drug intolerance, which was partially significant in the group of patients with rheumatoid arthritis (p less than 0.04; pc less than 0.3). This is an important argument in favour of the supposed protective role of this antigen.