The aim of this study was to evaluate the potential of Tc-99m citrate as a new tumor-localizing agent in palpable breast masses. Scintimammography was performed in 43 female patients. Of these, 10 women (group A) were considered to be healthy with no palpable breast masses, and the remaining 33 patients (group B) had palpable breast masses. All patients with palpable breast masses underwent fine-needle aspiration cytology and subsequent biopsy within 2 weeks of the study. Nine patients had a primary malignant lesion of the breast, whereas 24 patients had benign disease. The patients with breast cancer underwent surgery, and subsequently a histopathologic diagnosis was made. Sensitivity, specificity, and accuracy values obtained in our study were 87%, 100%, and 90%, respectively. Scintimammograms were performed in these patients up to 24 hours. Initial uptake at 1 and 3 hours was noted in all the breast masses. However, benign masses did not show persistence of tracer uptake at 24 hours, whereas those that were malignant continued to show persistent radionuclide concentration. Thus, the uptake and outflow pattern seemed to differentiate benign breast disease from breast cancer. The study shows the potential of Tc-99m citrate for imaging and evaluating breast masses.