OBJECTIVES: To perform a cost-effectiveness analysis comparing nanoparticle albumin bound (nab) paclitaxel (N-P, 260 mg/m2) with solvent-based paclitaxel (S-P, 175 mg/m2) given every 3 weeks as second-line treatment for metastatic breast cancer (MBC) from the perspective of the Portuguese National Health System (PNHS). METHODS: A Markov type stochastic process including disease states progression-free, progressive disease and death was designed to model long-term effectiveness and costs. Patient level data from a randomized, open-label, phase III study (n=460) was used to estimate parametric survival models (weibull) for time to treatment discontinuation, time to progression and time to death. Effectiveness was measured in life years (LY). Only direct costs were considered (drugs, medical visits, hospitalization, adverse events (grade 3/4) treatment and monitoring, terminal care). The source for unit costs was the PNHS price list. Time horizon was fixed at 4 years. Probabilistic sensitivity analysis was conducted with Monte Carlo simulations. Discount rates of 5%/year were applied to costs and effectiveness. RESULTS: A mean gain of 25 LY (95%CI: [2; 46]) was estimated for each 100 patients treated with N-P. This would represent an average 22% life expectancy increment. The estimated mean incremental cost of N-P treated patients was 7370 € (95%CI: [6762; 7945]). Corresponding average incremental cost-effectiveness ratio was 29,535€/LY. Probabilistic sensitivity analysis revealed an 83% probability of N-P to be cost-effective in comparison with S-P, at the commonly accepted threshold of 50,000€. CONCLUSIONS: nab-Paclitaxel may be considered a cost-effective drug as it adds a substantial relative increment in the overall survival over second-line solvent -based paclitaxel monotherapy in women with metastatic breast cancer. The estimation of long-term benefits of nab-Paclitaxel beyond the clinical trial follow-up period by Markov based modelling can provide valuable support to decision making in the context of scarce resources.