Accumulation of 99mTc-HMDP was recognized by three-phase bone scintigraphy in a case of primary breast cancer. A 67-year-old female was found to have a 14 x 13 mm mass in the upper lateral area of the left breast. At operation the histopathological finding was a proven solid-tubular carcinoma. On the first phase images, there was no abnormal accumulation in the tumor. On the second phase images, there was abnormal accumulation in the tumor, however, abnormal accumulation was observed followed by a decrease in accumulation. The third phase image showed no abnormal extra-skeletal accumulation. Color Doppler ultrasound sonography showed an abundance of color signals within the breast tumor. Increased 99mTc-HMDP accumulation in the second phase image might reflect tumor hypervascularization. It is concluded that three-phase bone scintigraphy using 99mTc-HMDP has the ability of positive description in primary breast cancer.