OBJECTIVES: The aim of this study was to assess the indirect costs caused by absenteeism associated with ankylosing spondylitis (AS) from the perspective of the Social Insurance Institution (ZUS) in Poland. METHODS: The estimates were based on data from the year 2013 concerning absence from work due to the illness (sick leave) the amount of short-term disability, the sufferers of which claim rehabilitation benefit, and the amount of long-term disability (permanent or fixed time), the sufferers of which claim disability pension. Costs were calculated taking into account Gross Domestic Product (GDP) per capita equaled €10 278, Gross Value Added (GVA) per worker equaled €24 680 and Gross Income (GI) per worker equaled €7 339 were presented in 2013 prices. RESULTS: Total indirect costs of AS in the year 2013 calculated using GDP per capita, GVA and GI per worker in Poland were €24 416 394, €58 631 008 and €17 435 690, respectively. The highest component of indirect costs of AS was permanent long-term disability (68%). Sick leave and short-term disability costs constitute 12% and 4% of total indirect costs of AS, respectively. In 2013 Poland’s Social Insurance Institution database reported 3 400 patients that had 7 137 sick leave episodes, 225 short-term disability episodes and 198 long-term disability episodes. Indirect costs per patient associated with sick leave were €894, €2 147 and €639 calculated using GDP, GVA and GI, respectively. Indirect costs per patient associated with short-term disability were €259, €622 and €185 respectively and associated with long-term disability were as high as €6 028, €14 474 and €4 304, respectively.  CONCLUSIONS: AS in Poland generated high indirect costs. The main component was permanent long-term disability; short-term disability generated lower costs of lost productivity. The highest cost per patient was generated by permanent long-term disability.