<h3>Background</h3> There is a lack of expertise in the rheumatoid arthritis (RA) diagnosis in primary level medical centers in Colombia, leading to misdiagnosis, which derives in wrong treatment for patients and pharmacoeconomic implications. <h3>Objectives</h3> The aim of this study was to describe demographic and clinical characteristics of a cohort of patients with misdiagnosis of RA in a specialized center in Colombia. <h3>Methods</h3> A descriptive, cross sectional study. Patients were referred from non-specialized centers to a RA specialized center in a 24 month period with presumptive diagnosis of this disease. A complete medical record was fulfilled by a rheumatologist; it was assessed rheumatoid factor and anti-citrullinated antibodies, and other laboratories depending on each case. Also were made x-rays of hands and foot, and in some cases of persistent doubt about the diagnosis was requested comparative MRI of hands. Frequencies and percentages were calculated for the demographic and clinical characteristics of the cohort of patients in which the diagnosis of RA was ruled-out. <h3>Results</h3> Of the 3665 patients evaluated, in 2214 patients (60.4%) diagnosis of RA was confirmed, the remaining 1451 patients (39.5%) had a wrong diagnosis of RA. Of these misdiagnosed patients, 1009 (69.5%) were women, and 442 (30.5%) men, with an average age of 59.7 (±12 years). Between differential diagnosis which were found in this cohort of misdiagnosed patients: osteoarthritis in 1116 patients (76.1%), systemic lupus erythematosus (SLE) in 85 patients (5.8%), Sjögren syndrome in 62 patients (4.3%), spondyloarthropathies in 22 patients (1.5%), gout in 32 patients (2.2%) and other diagnoses in the remaining population (8%). <h3>Conclusions</h3> Almost half patients with presumptive RA diagnosis in primary care centers in Colombia are misdiagnosed as shown in this large cohort. The most important cofounding diagnosis was osteoarthritis and many patients were receiving DMARDs for treatment. For this reason there is an urgent need of education strategies for primary care physicians and the implementation of centers of excellence in RA, in order to conduct a proper diagnose and avoid clinical and pharmacoeconomic consequences of misdiagnosis. <h3>Disclosure of Interest</h3> None declared <h3>DOI</h3> 10.1136/annrheumdis-2014-eular.5327