Objective: To compare the cost and utility of adjuvant Goserelin and adjuvant chemotherapy for premenopausal breast cancer patients in Taiwan. Methods: A total of 564 premenopausal breast cancer patients were newly diagnosed since 1993. Their medical history and vital status were routinely reviewed and recorded. From July 2007 to December 2007, 105 patients with stage Ia-IIIa disease who received Goserelin for at least one year or received at least 6 cycles of chemotherapy as adjuvant therapy were interviewed to obtain the utility value by standard gambling (SG) and visual scale (VS) methods. The chemotherapy included four regimens: CMF (cyclophosphamide, methotrexate, 5-fluorouracil), TE (docetaxel, epirubicin), TEC (docetaxel, epirubicin, cyclophosphamide), and CEF (cyclophosphamide, epirubicin, 5-fluorouracil). The cost of this study was defined as the total medical cost (surgery, drugs, and all services provided costs) of standard practices from a payer perspective. The standard practices of Goserelin and chemotherapy were subcutaneous injection of 3.6mg Goserelin every four weeks for two years and six cycles of CMF, TE, TEC, or CEF, respectively. Survival analysis was conducted by Kaplan-Meier method and weighted by utility measurements. Results: Survival at 11 years derived from registry data for patients received Goserelin was better than patients received chemotherapy (100% vs. 75%). Combining the survival data with utility score from questionnaires, the utility-weighted life-years were higher in Goserelin group compared to chemotherapy group by SG and VS 8.81 vs. 6.83, 8.78 vs. 7.14, respectively. The cost of Goserelin was lower than that of chemotherapy and ranged from NT$29,825 to 50,234 (US$918-1,545) when applying standard body surface of 1.5 m2 and 1.8 m2 about the calculation of chemotherapy doses. Conclusion: Our data suggest the Goserelin had better survival, higher utility-weighted life-years, but less cost than chemotherapy in the adjuvant treatment of premenopausal patients with stage Ia-IIIa breast cancer in Taiwan.