OBJECTIVES: to estimate the cost of Ankylosing spondylitis (AS) in Colombia. Background: AS is part of a group of pathologies of the spine called Spondylo-arthropathies, characterized by low frequency but with a severe disability, and high requirements of medical resources and costs.  METHODS: A structured survey was answered by seven rheumatologists in the country, in order to determine patterns of medication usage, management of adverse events, monitoring practice and follow-up of patients with AS in a year. Valuation of health resources and procedures were based on national standard tariffs (ISS 2001 + 30% and SOAT 2014). Medication prices were obtained from SISMED and price regulation official documents. Costs are reported in local currency (COP) RESULTS: Average annual cost of NSAIDs COP 105,509 pesos (range: COP 5,219.5 to 151,986). Second line DMARDs cost range between COP 3,104.33 and 4,307,000.  Biologic antiTNF annual cost fluctuates towards COP 28.661.464 and 30.264.000.  Monitoring and follow up costs range between COP 3.741.018 and 6.445.367. High uncertainty in expected adverse events costs between COP 6.558 to 3.382.456 per year. CONCLUSIONS: The AS is a disease represents a high economic burden for health system in Colombia.