Patients admitted to a prospective study within a year of onset of suspected rheumatoid arthritis showed a positive correlation between HLA-Dw4 and the eventual severity of peripheral radiologic changes. Dw4 and DR4 were strongly associated with severity of erosions when analysis was restricted to each of the following: patients with erosions, those under 50 at onset, and all females. Relationships were consistently stronger with Dw4 than with DR4. Another D-related specificity, MT3, was positively correlated and Dw2/DR2 negatively correlated with erosions.