BACKGROUND: Breast cancer is the one of the commonly diagnosed female cancer in Korea. Numerous factors have been noted to be associated with risk of breast cancer: body mass index, menarche, menopause, family history, pregnancy and delivery, breastfeeding, alcohol use, smoking habits, diet, education and use of oral contraceptives. Little is known about hair minerals in breast cancer patient and about correlation between hair minerals and body mass index. METHODS: We compared hair mineral analysis data of 37 breast cancer subject with age and body mass index-matched normal control data (N = 144) by cross-sectional analysis. All breast cancer patients were newly diagnosed at one Breast Cancer Center in Ajou University and had their hair cut before anti-cancer chemotherapy, and the normal controls (without breast cancer) also had their hair cut for various reasons in out-patient clinics of the Department of Family Practice and Community Health. RESULTS: Breast cancer patients had low calcium, magnesium, and zinc, whereas they had high arsenic, sodium, and potassium compared with the normal controls. Only hair zinc level had significant negative correlation with body mass index (r = -0.705, P < 0.001) in breast cancer patients, not in normal controls. CONCLUSION: We observed the difference of hair mineral patterns in newly diagnosed breast cancer patients compared to normal controls and the correlation between these minerals and body mass index in breast cancer patient. Especially hair zinc concentration was significantly reduced and had significant negative correlation with body mass index in breast cancer patients.