OBJECTIVE Information from successive inception cohorts is needed to reveal changes in the endpoint severity of rheumatoid arthritis (RA). We assessed joint destruction and disability 8-20 years after the onset of RA to estimate the number of patients with severe disease at the endpoint. METHODS Radiographs of the hands and feet were taken at onset and at 1, 3, 8, 15, and 20 years from entry among 103 patients with recent onset (< 6 mo) seropositive RA. The Larsen score of 0-100 of 20 joints of hands and feet, the Health Assessment Questionnaire (HAQ) index, and the number of large joint arthroplasties were used to assess severity. The cumulative number of patients with amyloidosis was recorded. RESULTS The median progression of small joint destruction was 2-3% yearly. At the endpoint 36% of the patients had Larsen score 50-100 and 23% scored 67-100. The endpoint HAQ index was 2-3 in 16% of the 81 patients investigated. The number of large joint arthroplasties was 29 in 16 patients. A high Larsen score or HAQ was registered in 30 (29%) patients. The incidence of amyloidosis was 13.6%; at the end of the 20 year followup 9 of the 14 patients with amyloidosis had died. CONCLUSIONS Our prospective 20 year RA study is the first epidemiological survey in which 20 year severity in RA has been determined by 4 clinical measures; these data will serve as a basis for discussion of methods and comparison with other cohorts in the future.