Thirty-eight female patients (age range: 31-79 years) with breast masses underwent technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) breast scintigraphy in order to assess the value of this technique in the detection of breast carcinomas and in their differentiation from benign breast masses. The results showed that 27 of the 32 cases of breast carcinoma were detected by 99mTc-MIBI breast scintigraphy. In contrast, none of the six benign lesions could be detected by this method. The diagnostic sensitivity, specificity and accuracy were 84%, 100% and 87%, respectively, in the differentiation of malignant and benign breast masses. In conclusion, we consider 99mTc-MIBI breast scintigraphy is useful in distinguishing malignancies from benign breast masses.