OBJECTIVES: There is a lack of data on bone loss in premenopausal patients with breast cancer after chemotherapy in Korea. In this study, we compared the bone mineral density of breast cancer patients after chemotherapy with normal control. MATERIALS AND METHODS: We used the data from the fourth Korea National Health and Nutrition Examination Survey (KNHNES) as normal control, and 119 women were enrolled who had surgery and chemotherapy due to breast cancer. They were under the age of 50 and premenopausal state according to their FSH level. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry. RESULTS: T-score at Lumbar spine BMD was not different between breast cancer group and control group (0.16+/-0.98 vs 0.08+/-1.00, P=0.451). And neither did T-score at femoral neck (-0.18+/-1.09 vs -0.27+/-0.95, P=0.419). T-score at total hip BMD was significantly different between two groups (0.26+/-0.97 vs 0.64+/-0.91, P<0.001). After adjustment of age and body mass index, the significance still remained (P<0.001 and P=0.001, respectively). The prevalence of bone loss (osteopenia and osteoporosis) at total hip was higher in breast cancer group than control group (10.1% vs 5.5%, P=0.012) CONCLUSIONS: The patients with breast cancer needs to evaluate the bone mineral density at total hip even if they are premenopausal states.