The aim of the study was to see whether rheumatoid arthritis (RA) is becoming a milder disease. Information on the initial disease activity and patient function (modified Health Assessment Questionnaire-HAQ) was collected in all RA patients enrolled into studies of sulphasalazine since 1980 in two Glasgow teaching hospitals. Patients (352) were enrolled in trials in the decade 1980-1989, and were compared to 374 patients enrolled in 1990-1994. Patients recruited in the 1980s were significantly younger, but had a similar disease duration to the 1990s patients. The 1980s patients had more active disease as measured by erythrocyte sedimentation rate (61 vs 44, P < 0.0001) and C-reactive protein (40 vs 26, P < 0.0001), and significantly worse function (HAQ 2.3 vs 1.9, P < 0.001). The response to sulphasalazine was very similar in the two cohorts, in terms of the percentage of patients remaining on therapy for 6 months, and the percentage improvement in measures of disease activity. Patients with milder disease were enrolled into the more recent trials of sulphasalazine. This may be because RA is becoming a milder disease, but other possible explanations are discussed.