We experienced changes in ultrasonographic features of hepatic parenchyma in 156 patients treated with Tamoxifen (TAM) as an adjuvant hormonal therapy for breast cancer. After the treatment with TAM subsequent to the surgery for breast cancer, 36% of patients showed changes in ultrasonographic features of the liver more than Grade 2, despite no obvious hepatic involvement at the start of the medication. Forty-five percent of affected patients showed Grade 2 or 3 changes in hepatic parenchymal images within the first 6 months of TAM medication, while the average interval of change was 11.3 months. Abdominal ultrasound inspection should be undertaken within 6 months of surgery to aid the early detection of liver metastasis and fatty liver changes, which may play an important role in determining postoperative follow-up care for breast cancer patients.