The first Finnish early rheumatoid arthritis (RA) cohort was established in 1973-75 at the Rheumatism Foundation Hospital in Heinola, a hospital for rheumatic diseases only. Since then early RA cohorts for the purposes of longitudinal observation have been established at the Jyväskylä Central Hospital and Helsinki University Hospital. Furthermore, 199 patients with early RA were enrolled in a multicenter randomized controlled study in 1993-95. The primary observations from these cohorts are summarized in this essay.