PURPOSE: To compare the usefulness of real-time compound US (RCUS) with that of conventional US (CUS) and pulse inversion harmonic (PIH) imaging in the diagnosis of malignant breast tumors. MATERIALS AND METHODS: In 22 female patients whose mean age was 49 years, we evaluated the RCUS findings of pathologically proven [core biopsy (n=9), mammotome tissue bigpsy (n=10), excisional bispsy (n=3)] malignant breast tumors, comparing them with the findings of CUS and PIH imaging. Evaluation of these masses was in terms of their marginal distinction, internal echogenicity, boundary and posterior echo pattern, relationship with the adjacent lactiferous ductal system, and the presence of necrosis (12/22) and calcification (6/22). RESULTS: In terms of marginal distinction, internal echogenicity, boundary echo patterns, and the relationship with adjacent ductal system, RCUS was superior to both conventional US and PIH Imaging (p<0.05). CONCLUSION: For the diagnosis of malignant breast tumors RCUS was more useful than CUS or PIH imaging.