Objective: To identify factors predicting the progression of Early Inflammatory Arthritis (EIA) to Rheumatoid Arthritis (RA). Design: This was a prospective longitudinal study. Methods: Inflammatory rheumatism that could not be classified according to defined rheumatism criteria. Demographic, biological, immunological and radiographic data were collected at the time of inclusion in the study. Disease activity as determined by the Disease Activity Score 28-CPR (DAS28- CPR: 4 variables), functional handicap as calculated by Heath Assessment Score (HAQ), and bone and joint damage as evaluated by Sharp-Van der Heijde (SVDH) score. Ultrasound joint imaging were evaluated at the beginning of the study and then 1 year later. Logistic regression was performed to identify predictive factors for progression to RA. Results: One hundred and seventy two patients were included (24 men, 148 women), with a mean age 43.13±14.07 years and a mean time to diagnosis 10.24±6.84 months. The mean ESR was 46.81±31.16 mm/1st hour, and the mean CRP level was 22.84±39.8 mg/l. Rheumatoid Factors (RFs) and Anti-Citrullinated Protein Antibodies (ACPAs) were present in 48.8% and 53% of patients, respectively. The erosion, joint space narrowing, and total SVDH scores were 3.38±3.48, 5.08±3.32, and 5.95±4.94, respectively. One hundred and sixty one patients were followed up for 12 months. Multivariate regression analysis showed that a DAS28-CRP level >5.2 (OR=28.6; CI 95% 8.7-94.5), an RF level >60 IU/L (OR=11.2; CI 95% 4.3-87.5), and an ACPA level >60 IU/L (OR=5.4; CI 95% 1.9-15.3) were predictive for progression to RA. Conclusion: Our study suggests that clinical evaluation of EIA by DAS28- CRP from the time of diagnosis, as well as evaluating the presence of RA autoantibodies, can predict progression to RA. Key words: Early inflammatory arthritis, Rheumatoid arthritis, Predictive factors