The aim of the study was to evaluate the possible role of scintimammography (SMM) with technetium-99m tetrofosmin in breast cancer. Thirty-three patients with breast disease and ten normal controls were included in the study. Planar scintigraphic images in supine anterior, prone lateral and lateral views, with the patient lying in lateral recumbency, were acquired. A qualitative analysis evaluating both breasts and lymph nodes was performed. All breast lesions were verified after surgery and/or by fine-needle aspiration. In 8 of the 33 patients, mammography was inconclusive because of mastectomy or dense breasts. For mammography, a sensitivity of 95.6%, a specificity of 66.7% and an accuracy of 89.6% were obtained. At SMM, 26 out of 28 malignant lesions (average size 2.8 cm, range 0. 4-12 cm), including two recurrences, were detected with a 92.8% sensitivity, a 100% specificity and a 95.1% accuracy. The smallest detectable carcinoma measured 0.6 cm. Two false-negative results on SMM were found in a 0.4-cm intraductal carcinoma and in the only mucinous papillary carcinoma in our series. With regard to lymph node analysis, 11 out of 12 axillary metastases (sensitivity=91.6%) were detected. A false-positive result, yielding a specificity of 92. 3% was also obtained. A metastatic involvement of the internal mammary chain was observed. No uptake was seen in 11 benign mammary lesions or at the level of the breast and axilla when neoplastic involvement was absent. In conclusion, SMM with 99mTc-tetrofosmin is an effective technique for the evaluation of primary breast carcinomas, recurrences and lymph node metastases.