5-fluorouracil, epirubicin, cyclophosphamide → docetaxel (FEC-D) has been associated with higher-than-expected rates of febrile neutropenia (FN) that meet the current guideline threshold of 20 % for primary prophylaxis (PP) with granulocyte colony-stimulating factor (G-CSF). We examined the cost-effectiveness of FEC-D with varying strategies of G-CSF prophylaxis from the perspective of the public payer in Ontario, Canada. A state-transition model was developed to compare three strategies: FEC-D with secondary prophylaxis (SP) only, PP starting with the first cycle of D, and PP starting with the first cycle of FEC. Analysis was conducted for a hypothetical cohort of 50-year-old early-stage breast cancer patients undergoing adjuvant chemotherapy, at a 10-year horizon. Results were expressed in quality-adjusted life-years (QALYs) and 2013 Canadian dollars. Costs and benefits were discounted at 5 %. Event rates, costs, and utilities were derived from the literature. One-way and probabilistic sensitivity analyses were conducted. Using filgrastim, the incremental cost-effectiveness ratios (ICERs) for starting PP with the first cycle of D and starting PP with the first cycle of FEC, compared to using SP only, were $57,886/QALY and $116,186/QALY, respectively. With pegfilgrastim, the ICERs for the same strategies were $90,735/QALY and $149,483/QALY. Compared to using filgrastim SP only, starting PP with D had a 24 % chance of being cost-effective at a willingness-to-pay (WTP) threshold of $50,000/QALY, and a 99 % chance at a WTP threshold of $100,000/QALY. Results were sensitive to FN-related parameters, such as the risk of FN per cycle with D and the associated mortality, but were robust to uncertainty in parameters related to breast cancer, such as the utilities and hazard of relapse. FEC-D with PP starting with the first cycle of D is most likely to be cost-effective, especially with increased risk of FN and mortality from FN.