OBJECTIVES:  Recently, a house dust mite (HDM) sublingually administered allergy immunotherapy tablet (SQ® HDM SLIT-tablet; ACARIZAX®) has been developed for at-home treatment. The objective was to assess the cost-effectiveness of ACARIZAX® for the treatment of patients with allergic rhinitis (AR) and/or allergic asthma (AA) in comparison to standard of care (pharmacotherapy) in the Czech Republic. METHODS:  Decision tree models were developed based on the pivotal clinical trials MT-04 (AA) and MT-06 (AR) with a 5-year time-horizon. The choice of comparator was in line with the clinical trials, i.e. standard pharmacotherapy in addition to either ACARIZAX® SLIT-tablet or placebo SLIT-tablet. Utility values and healthcare utilisation values used in the models were taken from the pivotal clinical trials. The direct costs were adopted for Czech settings. RESULTS:  A HDM AR patient treated with ACARIZAX® for three years as add-on to pharmacotherapy generates costs of 95 953 CZK in the five year time horizon in comparison to 4 296 CZK generated by a patient treated with pharmacotherapy only. An ACARIZAX® patient on the other hand gains 4.33 quality-adjusted life-years (QALYs); a pharmacotherapy patient gains only 4.19 QALY in the same time horizon. HDM AA ACARIZAX® patient generates costs of 119 217 CZK and gains 3.59 QALY in 5 years. HDM AA patient treated only with pharmacotherapy costs the payers 16 199 CZK and generates 3.40 QALY in the same time horizon. Final incremental cost-effectiveness ratio for a HDM AA patient is 0.54 mil CZK/QALY and for HDM AR patient 0.68 mil CZK/QALY. CONCLUSIONS:  Considering the willingness to pay threshold of 1,27 mil. CZK (3xGDP per capita in year 2015), ACARIZAX® shows to be cost-effective treatment for the target population in comparison to pharmacotherapy.