OBJECTIVES: Describe the adverse drug reactions (ADR) and their incidence in patients with rheumatoid arthritis who were treated in the Colombian Heath System.   METHODS: Retrospective cohort study using information from all patients who were diagnosed with rheumatoid arthritis and attended Specialized Institution centers in the cities of Bogotá, Cali, Manizales, Medellin and Pereira between December 1^st, 2009 and August 30^th, 2013. The ADRs were obtained from medical records and the pharmacovigilance system register and were sorted by frequency and affected tissue according to WHO Adverse Reaction Terminology (WHO-ART). RESULTS: A total of 949 ADR reports were obtained from 419 patients with an incidence of 32.8 ADRs per 100 patient-years; these were from a cohort of 1,364 users followed for an average of 23.8±12.9 months. There was a female preponderance (n=366, 87.4%) and a mean age of 52.7±13.1 years. The highest incidence rates for ADRs were reported for tocilizumab, rituximab and infliximab with 28.8, 23.1 and 13.3 reports per 100 patient-years respectively. The most frequent were "Elevated transaminase levels" and "Dyspepsia". Overall, 87.7% of ADRs were type A; 36.6% were classified as mild, 40.7% as moderate and 22.7% were severe. As a result, 73.2% of patients who experienced an ADR stopped taking their drugs.   CONCLUSIONS:  the occurrence of ADRs in patients treated for rheumatoid arthritis is common, especially in those associated with the use of biotechnologically produced anti-rheumatic drugs. This should be emphasized in reports and monitoring is needed to reduce the risks in these patients.