PURPOSE: To report some early experiences of ultrasonography-guided mammotome biopsy for solid breast lesions. MATERIALS AND METHODS: Sixty seven solid breast lesions in 59 patients aged 25 -77 (mean, 44.5) years were biopsied under ultrasound-guidance using an 11 gauge mammotome. The size and depth of the lesions, diagnostic accuracy achieved, complications, and merits and demerits of the device were evaluated. RESULTS: The lesions ranged in size from 0.5 to 8 (mean, 1.6)cm, and at their center the mean depth was 1.4 cm. For every lesion at least seven biopsies were performed, and the mean weight of extracted tissue was 0.44 gm. The lesions were located mainly at the at 12 o'clock area and upper inner quadrant of the left breast (n=10 for each area); they were also found in other regions fo both breasts, including subareolar areas. The histopathologic diagnosis was malignant in 26 lesions and benign in 39, and in one case, atypical ductal hyperplasia was diagnosed. One lesion contained no tumor cells. Twenty-four malignant lesions were surgically excised, and in 21 invasive ductal/lobular carcinomas and one ductal carcinoma in situ (DCIS) (91.7%) the initial and subsequent diagnosis correlated. One lesion diagnosed as DCIS and one whose invasiveness could not be initially determined were confirmed as invasive ductal carcinomas (8.3%). Follow-up ultrasonography involved six benign lesions and showed that five of these had become smaller. The complications noted were severe pain in three patients and a moderate amount of bleeding in two, but in all cases good control was achieved by interrupting the procedure or applying compression. The merits of the mammotome biopsy compared with the conventional core biopsy technique are higher diagnostic accuracy due to the larger amount of tissue extracted by suction and the large caliber of the needle, multiple biopsies achieved by one needle insertion, and less possibility of severe complications such as pneumothorax. Drytapping was a demerit of the device. Very small lesions could be extracted completely, and this may be a merit for benign lesions and a demerit for malignant lesions. For the latter, clips could be used. CONCLUSION: Ultrasonography-guided mammotome biopsy is a very accurate and safe method for the diagnosis of various breast lesions.