OBJECTIVES: To determine direct and indirect cost due to rheumatoid arthritis (RA) and ankylosing spondylitis (AS) in Turkey. METHODS: An expert panel composed of 21 experts chosen from all national tertiary care rheumatology units (n=53) was convened to estimate the direct and indirect costs of care of patients with RA and AS in Turkey, using “cost-of-illness” methodology. To measure indirect costs, the number of days of sick leave, the extent of disability, and the levels of early retirement and early death were also evaluated. Lost productivity costs were calculated using the “human capital approach”, based on the minimum wage. RESULTS: The total annual direct costs were 2.917,03 Euro per RA patient and 3.565,9 Euro for each AS patient. The direct costs were thus substantial, but the indirect costs were much higher because of extensive morbidity and mortality rates. The total annual indirect costs were 7.058,99 Euro per RA patient and 6.989,81 for each AS patient. Thus, the total cost for each RA patient was 9.976,01 Euro and that for an AS patient 10.555,72 Euro, in Turkey. CONCLUSIONS: From the perspective of those who pay for health care, both RA and AS has become a burden in Turkey. The cost of lost productivity is higher than the medical cost. Another important conclusion is that indirect costs constitute 70% and 66% of total costs in patients with RA and AS, respectively. The annual cost of RA for whole Turkish population is 2.130.424.680 Euro. This amount contributes to 0.37% of the GDP in Turkey. Whereas for AS, the annual cost of disease in Turkey is 2.209.201.904 Euro and this corresponds to 0.38% of the GDP. To conclude, RA and AS diseases have total burden of 4.339.626.584 Euro that is 0.75% of the Turkish GDP.