To analyze changes in baseline characteristics of very early rheumatoid arthritis (RA) over 24 years in the Early Undifferentiated PolyArthritis (EUPA) cohort. Consecutive recent-onset polyarthritis patients fulfilling RA classification criteria recruited in EUPA were assessed at baseline. Three successive periods were defined: prior to the general availability of biologics (1998-2004; 245 patients), prior to the implantation of the 2010 classification criteria (2005-2010; 266 patients), and the most recent decade (2011-2022; 329 patients). At baseline, demographics, BMI, swollen and tender joint counts, proportion fulfilling 2010 ACR⁄EULAR criteria, Modified Health Assessment Questionnaire, shared epitope status, patient-reported outcomes except pain and Patient Evaluation of Disease Activity remained stable over the 3 periods. Despite a marked decrease in active smoking (22.2 to 12.1%), prevalence of cardiovascular comorbidities and prior cancer increased. While duration of symptoms increased from 2.9 to 4.1 months, seropositivity (53.9 to 42.2%), and CRP began decreasing in the 2005-2010 period. A large decrease in Erosive status (Sharp-van der Heijde erosion score ≥5; 18.3 to 9.4%) was only observed after 2011; this decrease occurred mostly in seronegative patients. DMARD use prior to inclusion remained low and stable (25.7%), but oral corticosteroids increased (18.0 to 33.4%). Baseline characteristics of RA patients evolved since 2005 towards less seropositivity and lower blood inflammation but with more comorbidities. Milder erosive damage at baseline became evident only since 2011, mostly in seronegative patients. These changes at baseline, before any intervention, suggest ongoing secular trends that may favorably impact early RA patients' outcomes.