HLA-A, B, C, D, and DR typing was performed in 104 patients with Juvenile Chronic Arthritis (JCA). The majority of these (88 patients) participated in a follow-up study of a series of consecutive patients including patients in remission. The study confirmed that JCA is positively associated with B27, Dw8, and possibly Dw5, and negatively associated with Dw2 and Dw7. In JCA patients in remission, the frequency of Dw4 was significantly decreased to 5.0%, compared with 25.0% in healthy Danes and 23.7% in JCA patients with active disease. In pauciarticular onset JCA, the frequency of Dw4 was significantly decreased to 8.1% compared with 25.0% both in controls and in polyarticular onset JCA. These data indicate that Dw4 may be a risk factor of chronicity and multiple joint involvement in JCA. Chronic iritis was present in 18.2% of Dw8-positive patients, compared with 7.0% in Dw8-negative patients, and the frequency of Dw8 was 50.0% in JCA patients with chronic iritis. Thus, Dw8 may be a risk factor of chronic iritis in JCA. Genetically, three distinct subgroups seem to exist: (i) a B27-associated group; (ii) a D/DR5- and D/DRw8-associated group, and (iii) a D/DR4-associated group.