Objective: Splenectomy, thrombopoietin receptor agonists and rituximab are the second-line treatments for steroid-resistant adult primary immune thrombocytopenia. The last two are becoming the most widely used treatments to avoid splenectomy adverse effects and inconveniences. However, the choice between rituximab and thrombopoietin receptor agonists is unclear. Therefore, the treatment cost may be of particular interest to prioritize the therapy option. Our aim is to determine the cost per responding-patient after 6 months of use of rituximab compared to thrombopoietin receptor agonists eltrombopag in the treatment of chronic primary immune thrombocytopenia in the Spanish National Health Service. Method: A 26-week decision tree model was developed to assess the cost of treatment response of adult patients with chronic-refractory primary immune thrombocytopenia to eltrombopag and rituximab from the perspective of the Spanish National Health System. Effectiveness was obtained from the literature, and cost was obtained from the official rates. Costs were expressed in € (2018). Due to the short period of assessment, no discount rate was applied. Results: The average cost per patient after 6 months of treatment was slightly higher for eltrombopag (€13,089.40) than for rituximab (€11,852.60). However, the greater response rate of eltrombopag decreases the bleeding costs, resulting in a 29% higher cost per responding-patient with rituximab (€18,964.15) than for eltrombopag (€14,732.65). This result is consistent with the results of the 15 sensitivity analyses carried out where eltrombopag always represents a lower cost per responding patient, except in the sensitivity analysis in which treatment with eltrombopag is performed at its maximum dose (75mg). Only in this case, the cost per responder of eltrombopag is €48 more expensive than that of rituximab. Likewise, the greatest difference in favor of eltrombopag occurs in the scenario that uses the minimum dose of this drug —25mg— (eltrombopag €7,622.14 compared to €18,964.15 for rituximab). Thus, the cost per responding patient is lower in eltrombopag even if a second cycle of retreatment with rituximab is not performed (€14,732.65 versus €15,298.61). Conclusions: The treatment cost of rituximab, including monitoring and bleeding costs, is higher than eltrombopag, favoring the latter over rituximab treatment.