Objective A new silicone-suppressed MR technique was developed, and its efficacy in identifying free silicone and differentiating it from other breast tissues was investigated. Materials and Methods Silicone-suppressed MRI was performed using the RODEO (rotating delivery of excitation off-resonance) pulse sequence, which selectively eliminated signal from the narrow range of (CH3)4Si resonance. Ninety breasts in 61 patients were evaluated with both a fat-suppressed 3D MR sequence and a silicone-suppressed 3D MR sequence. Results Extracapsular free silicone and silicone injections demonstrated a unique appearance compared with normal breast tissue in all cases. Magnetic resonance identified free silicone in 26 breasts, 10 of which were confirmed pathologically or from a history of previous silicone injections. No free silicone was present on MR in 64 breasts; 8 of these were confirmed by biopsy or mastectomy as showing no evidence of free silicone. This technique was useful in evaluation of prosthesis integrity, free silicone, focal palpable or mammo-graphic lesions, and the breast with silicone injections. Conclusion Silicone-suppressed RODEO MRI of the breast can accurately identify free and intracapsular silicone and can distinguish silicone from other tissues. This provides unique information about the breast in a number of specific applications.