OBJECTIVES: To assess the impact of ankylosing spondylitis (AS) on work productivity, to determine factors influencing work productivity and to estimate productivity costs incurred by AS in the Czech Republic. METHODS: A questionnaire including Work Productivity and Activity Impairment Questionnaire (WPAI:AS), Health Assessment Questionnaire (HAQ) and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) were filled out by 230 patients with AS in productive age. The interdependence between HAQ, BASDAI, disease duration, age and WPAI:AS scores were described by Spearman´s rank correlation coefficient. We have analyzed differences between work-active and all patients (work-active + disable) groups, effect of biological treatment and education level on work productivity. Productivity costs were calculated by friction cost approach (FCA) using friction period of 130 work-days and average monthly gross income as denominator. RESULTS: Average patients´ age was 49.3 years (22-61) and average disease duration 18.0 years. Mean HAQ and BASDAI were 0.99 and 4.43, respectively. We reported significantly greater loss in work productivity (p-value<0,001) and daily activities impairment (p-value<0,001) for disable patients in compare to work-active patients, differences were by 35.6% and 19.6%, respectively. AS in work-active patients group was associated with 40.7% reduction in work productivity and 40.3% reduction in daily activities. Work-active patients group revealed significantly lower age (p-value<0,001), lower BASDAI (p-value<0,001) and lower HAQ (p-value<0,001). Work absenteeism was weakly correlated with BASDAI and HAQ. Work presenteeism and overall work impairment were moderately correlated with BASDAI and HAQ, whereas impairment of daily activities was strongly correlated with all four  WPAI domains. Average annual productivity costs per one patient were €2923 in all patients group. CONCLUSIONS: HAQ, BASDAI and age significantly influence patients’ productivity. Patients on biologics had lower impairment of daily activities and work productivity and revealed lower HAQ and BASDAI as well. Average annual productivity costs per one patient were €2923.