Objective:To explore the feasibility of monitoring liver fat content changes by proton maganetic resonance spectroscopy (1H-MRS) in patients with cancer of mammary gland. Methods:Thirty patients with breast cancer who were receiving postoperative chemotherapy were included. 1H-MRS was acquired before chemotherapy,after three or six cycles treatment. All scans were performed on GE 1.5T MRI system using point-resolved-spectroscopy sequence,and breathing gating were employed. Fat content was calculated by measuring the areas of water and lipid peaks using jMRUI software package. Results:Hepatic fat content increased in 26 patients (26/30) after treatement. Among these patients 21 cases had lipid peak before treatment and the value increased from(5.59 ± 4.86)% to (8.79 ± 6.02)% after three cycles,and reached(15.81 ± 10.73)% after six cycles of treatment. The other 5 patients who had no lipid peak before chemotherapy showed lipid peak during treatment. There were 4 cases (4/30) without showing lipid peak during the whole chemotherapy course. Conclusion:Hepatic fat content increased during chemotherapy in breast cancer patients. 1H-MRS provides a noninvasive tool to monitor hepatic fat content change and detect chemotherapy related liver toxicity.