Background: The impact of neoadjuvant endocrine therapy (NET) on health-related QOL (HRQOL) has not been clarified yet. N-SAS BC 06 is a multicenter study in postmenopausal patients with hormone-sensitive primary breast cancer, two-staged (preoperative and postoperative) enrollment, and intervention. It includes a randomized controlled study of patients responding to NET, which is designed to compare chemotherapy followed by endocrine therapy, with endocrine therapy alone, as postoperative adjuvant therapy. The primary endpoint is DFS, and the secondary endpoints include adverse events, HRQOL and health economic evaluation. This report presents the planned analysis of HRQOL during 6 months of NET. Methods: The target sample size was 850 patients of whom the first 500 enrolled patients were included in HRQOL evaluation. Subjects were assessed at enrollment, and at 1 and 4 months after starting NET, using FACT-G (General), B (Breast), ES (Endocrine Symptoms) and HADS (Hospital Anxiety and Depression Scale). Results: Mean age was 63 years, mean BMI was 23.9. Results of clinical efficacy were as follows: CR: 2%; PR: 44.3%; SD: 48%; and PD: 5.7%. The questionnaire response rates at enrollment, and at 1 and 4 months were 93%, 90% and 82%, respectively, quite a high response rate. The mean scores at enrollment, and at 1 and 4 months were as follows: FACT-G: 82.9; 83.4; 82.7, FACT-B TOI (Trail outcome index): 68.3; 69.5; 68.9; ES subscale: 61.2; 60.1; 59.7 and HADS score: 10.4; 8.9; 8.8 respectively. There were no significant changes in the FACT-G or B-TOI over time, while the social domain score, ES subscale, decreased significantly (worse social well-being and ES). In the ES analysis by item, symptoms such as hot flash showed a greater decrease. HADS scores deceased significantly (improved anxiety and depression), and emotional domain scores increased significantly (better emotional well-being) at 1 month and 4 months after NET. Conclusions: NET had no impact on the overall HRQOL scores, but the anxiety and depression observed at enrollment had improved by 1 month after therapy. To our best knowledge, this is the first report of HRQOL during NET. Clinical trial information: 000001090.