Rotating delivery of excitation off-resonance (RODEO) is a new magnetic resonance (MR) imaging pulse sequence that uses a jump return sine excitation on fat resonance to produce fat-suppressed, T1-weighted images. New three-dimensional MR imaging techniques were used to examine 57 women with abnormalities suspicious for breast cancer. MR imaging findings were compared with those of mammography in all cases and with those of other imaging techniques when appropriate. Thirty-five specimens obtained at mastectomy were analyzed with rigorous pathologic examination that included imaging of the entire breast at 5-mm incremental sections. Histologic confirmation was obtained in 76 lesions in 47 patients. MR imaging helped detect 100% of malignant lesions, whereas mammography produced 33% false-negative findings. The use of RODEO in breast imaging is in the early investigational phases, but it has potential for supplementing mammography in the diagnosis of breast cancer.