One hundred and fifty consecutive patients with active, rheumatoid arthritis were assessed and treated with gold, D-penicillamine, chloroquine or dapsone. Four groups were selected from these patients. Group I consisted of 60 patients who did not complete 12 months' therapy. Group II consisted of patients in whom ESR and C-reactive protein (CRP) fell to less than 30 mm/h and less than 20 mg/l, respectively, and remained at these levels between 6 and 12 months. In group IV the ESR and CRP fell but remained greater than 30 and greater than 20, respectively, during the same period. Group III patients had variable ESRs and CRPs between 6 and 12 months. In groups II, III and IV there was a significant deterioration (p less than 0.01) in the hand and foot radiographs from 0 to 6 months. Between 6 and 12 months the radiographs in groups III and IV continued to show significant radiological progression (p less than 0.01), but those of group II did not alter. These results suggest radiological deterioration continues during the first 6 months regardless of clinical response but thereafter, further deterioration is less likely to occur when the ESR and CRP are consistently controlled.