OBJECTIVES To assess the cost-effectiveness of romiplostim in the treatment of Adult Immune Thrombocytopenia (ITP) in Portugal, versus eltrombopag and current medical standard of care (SoC). METHODS A lifetime treatment-sequence cost-utility Markov model with an embedded decision tree was developed from the Portuguese Healthcare Payer perspective to compare romiplostim with eltrombopag and SoC in splenectomized patients, non-splenectomized patients and a combined population. Treatment sequences and health care utilization were validated by a Portuguese expert in ITP. Outcomes included incremental cost-utility ratio (ICUR). Costs (€, 2014) included drug acquisition costs and costs associated with monitoring patients and managing complications.  RESULTS In the combined population, romiplostim versus eltrombopag had incremental costs (IC) of 13.848€ and a quality-adjusted life-years (QALY) gain of 0,566, yielding an ICUR of 24.451€. Compared with SoC, romiplostim had IC of 18.622€ and a QALY gain of 0,938, yielding an ICUR of 19.848€. In splenectomized patients, the most prevalent sub-population in Portugal (65% of adult chronic ITP patients), romiplostim had an ICUR of 6.304€ versus eltrombopag and an ICUR of 3.179€ versus SoC. One-way sensitivity analysis showed that the model was most sensitive to variations in the drug doses/ percentage of utilization and costs (romiplostim, eltrombopag and intravenous immunoglobulin) and to the utility of patients responding to ITP treatments. In the combined population the probabilistic sensitivity analysis showed that romiplostim is likely to be cost-effective in 66% and 84% of samples versus eltrombopag and versus SoC at a willingness-to-pay threshold of 30.000€/QALY, respectively. CONCLUSIONS Use of romiplostim in the ITP treatment pathway, compared with eltrombopag or SoC, is likely to be cost-effective in Portugal.