OBJECTIVES: To estimate the cost-effectiveness of docetaxel for breast cancer treatment in adjuvant and metastatic settings. Three comparisons are performed: 3 cycles of fluorouracil, epirubicin and cyclosphophamide followed for 3 cycles of docetaxel (3FEC100-3D) versus 6 cycles of fluorouracil, epirubicin and cyclosphophamide (6FEC100); 6 cycles of fluorouracil, doxorubicin and cyclosphophamide (FAC) versus 6 cycles of docetaxel, doxorubicin and cyclosphophamide (TAC), both as adjuvant treatments; and docetaxel versus paclitaxel in metastatic breast cancer (MBC). METHODS: The lifetime Markov model used for the adjuvant setting analysis, developed by Aremis Consultants, considers 6-month cycles and 4 health states: no recurrence; loco-regional recurrence; metastatic recurrence; and death. The model for MBC, created by United Bio Source, lasts for 10 years with 3-week cycles and 3 health states: no progression; progression; and death. Transition probabilities were derived from head-to-head clinical trials. Direct medical costs were estimated for the Society and the tertiary cancer centre Instituto Português de Oncologia de Lisboa (IPOL) perspectives. Resource consumption was based on clinical practice at IPOL (patient-level data). Unit costs were derived from official sources and IPOL data. RESULTS: The  projected survival advantage was 0.93 years for TAC compared to FAC, with an incremental cost of €8369 for the Society and €8031 for IPOL, and 0.49 years for 3FEC100-3D compared to 6FEC100, with incremental costs below €3700 for either perspective. In both cases, incremental costs per life year gained (ICER) are below €9000. In MBC, the predicted incremental life expectancy with Docetaxel is 6 months, being the incremental cost of around €11,000 for either Society or IPOL. The ICER is €21,905 and €22,329, respectively. Sensitivity analysis shows that these findings are only responsive to changes in the relative clinical gains of docetaxel. CONCLUSIONS: Docetaxel is cost-effective and should be used as adjuvant treatment and considered as  therapeutic option for MBC.