Thirty one female patients(age range 23~71 years) with suspicious breast lesions underwent technetium-99m methoxyisobutylisonitrile(Tc-99m MIBI) breast scintigraphy in order to assess the value of this technique in the detection of breast carcinomas and lymph node metastasis. The results of this Tc-99m MIBI scintigraphy were compared with mammography and ultrasonography. The results showed that all cases of breast cancer were detected by Tc-99m MIBI breast scintigraphy. Eight of 15 axillary lymph node metastasis showed positive uptake(53%). The sensitivity of mammography and ultrasonography were 77% and 84% respectively. Every multiple lesions in four patients were detected preoperatively with Tc-99m MIBI scintigraphy. Our results suggest that Tc-99m MIBI scintigraphy may be useful in diagnosis of breast cancer.