OBJECTIVES:  Chronic lymphocytic leukemia (CLL) is a severe disease. Ibrutinib is an oral, first-in class Bruton’s tyrosine kinase inhibitor approved for treatment of relapsed/refractory (R/R) CLL. The aim of this paper was to estimate the 5 year budget impact of ibrutinib in the treatment of R/R CLL in the Czech Republic from a payer’s perspective and to show ibrutinib’s benefits. METHODS:  A patient-flow model was developed based on real-world data from the University Hospital Brno. The model works with yearly probabilities of relapse and death calculated from real-world data. These were calibrated so that the model keeps a stable structure of patient population corresponding with the real-world data. Number of patients was extrapolated to reflect the whole Czech Republic (524 patients start any treatment through all lines). Drug acquisition costs, hospital admission costs, administration costs, follow-up care and Best Supportive Care (BSC) costs were considered. RESULTS:  Net budget impact of ibrutinib in R/R CLL in 1^st year was estimated at EUR 1.116 mil. which represents 0.009 % of the national health care expenditure budget and 0.118 % of the oncology budget. Cumulative budget impact during five years was estimated at EUR 23.786 mil. which is 0.034 % of the national health care expenditure budget and 0.368 % of the oncology budget. Over a 5 year period, 222 patients will be treated with ibrutinib. Of these, 149 patients (67%) would remain alive after 5 years. Without ibrutinib, only 75 patients (34%) would remain alive after 5 years. CONCLUSIONS:  Ibrutinib treatment is associated with significantly prolonged survival and higher total costs largely due to ibrutinib continuous administration and longer PFS. As CLL is an orphan indication, the budget impact is negligible compared to total healthcare or oncology expenditures.