Fifty eight patients suffering from a recent onset of rheumatoid arthritis (RA) were studied. Fifty six patients were followed up for 24 months and two for 18 months. Erosions were detected in 17 patients at the onset and at the end of the follow up period the number of patients with erosions was 44. The erosiveness in the joint groups studied was as follows: metatarsophalangeal (MTP) (36 patients), metacarpophalangeal (MCP) (22), proximal interphalangeal (PIP) (21), interphalangeal (IP) joints of first toes and wrists (13), elbows and knees (two), and shoulders, ankles, and hips (one). Erosiveness in the feet was twice that in the fingers, and the erosions in the feet appeared at an earlier phase of disease. Destructions favoured the dominant hand. Swelling in the PIP joints appeared to be a better predictor of erosiveness than joint tenderness. The number of joints to become eroded was significantly increased in the patients with flexor tenosynovitis in the hands. Erythrocyte sedimentation rate (ESR) was more closely related to progression of joint damage than C reactive protein (CRP) or haemoglobin. The rate of development of new erosions was the same in seronegative and seropositive patients. In addition, HLA-DR4 allele did not correlate either with seropositivity or with erosiveness. Adequate antirheumatic drug treatment (gold in most instances) was not able to restrain the erosive process despite decreased rheumatoid disease activity.