Serologic HLA typing was carried out on 71 seropositive and 40 seronegative patients with rheumatoid arthritis and compared with values in 134 normal controls. A significant increase of HLA DR4 antigen, compared with control values, was found only in seropositive rheumatoid arthritis; HLA A1 and B35 antigens were significantly increased in seronegative rheumatoid arthritis patients (p less than 0.05), when compared with control values, but only HLA A1 antigen remained significantly higher when the p-correct test was performed.