OBJECTIVES: Determining cost-effectiveness of ECP in the treatment of patients with steroid-refractory GvHD after allogeneic HCT, as well as the impact of its reimbursement on the Polish public payer expenditures. METHODS: The evaluation of the cost-effectiveness of ECP was conducted separately for children/adults with acute/chronic steroid-refractory GvHD by means of Markov decision model. Due to the lack of standards of treatment for this group of patients and adequate clinical studies, analysis was performed without a comparator. Polish cost data were estimated from the perspective of the public payer (NHF). Discount rates 5% for costs and 3.5% for health outcomes were used. There was also calculated extra cost incurred by NHF caused by ECP reimbursement. Two scenarios were considered: the existing (no ECP reimbursement) and the new (ECP reimbursed) on the 2-year time horizon. For assuming current expenses incurred on GvHD treatment data published by NHF were used. Savings resulting from the decreased number of other health services used in GvHD treatment were not considered, so incremental cost consists merely of the costs of ECP procedure performed. Target population was estimated at 37-38 patients. RESULTS: The most favorable ratio of health benefits to costs of therapy in 3-year time horizon was achieved for treatment of adult patients with acute GvHD – CER ratio 24,103.30 PLN/LY. Others ratios of health benefits to costs are: 26,772.15 PLN/LY for children with chronic GvHD; 30,473.46 PLN/LY for adults with chronic GvHD and 35,854.39 PLN/LY for children with acute GvHD. After ECP reimbursement, annual expenses of the public payer on the treatment of acute and chronic GvHD are going to grow by 1,224,736-1,269,300 PLN (47.92%-49.66%) in the following years of the time horizon. CONCLUSIONS: ECP seems to be a cost-effective therapy for patients with steroid-refractory, acute and chronic GvHD with limited impact to Polish public payer budget.