Eighty five Arab patients with classical and definite rheumatoid arthritis were typed to determine the prevalence of HLA A, B, C, and DR antigens. A significant increase in the prevalence of HLA-A10, B8, B21, and DR3 was found in comparison with a control population matched for age and sex. HLA-DR5 was significantly decreased in the patient group. The classical association of HLA-DR4 with rheumatoid arthritis could not be confirmed in the Arab patients resident in Kuwait, supporting reported observations in different ethnic groups of associations with HLA antigens other than HLA-DR4 and indicating a heterogeneous genetic susceptibility to rheumatoid arthritis.