The authors evaluated the ability of ultrasound (US) in detection of silicone implant ruptures and compared US detection with that of mammography and physical examination in 22 women with 29 sites of implant leakage. On sonograms, leaks were evident from a highly echogenic pattern of scattered and reverberating echoes with loss of detail posterior to the echogenic area. The area appears as a "snowstorm" and has a well-defined anterior margin but a poorly defined posterior margin. Twenty-five sites in 19 women were surgically confirmed. Mammograms obtained with various views and sonograms were available for comparison in 20 of 25 surgically confirmed leaks. Of all 29 leaks, 14 were detected at physical examination as palpable masses. Six of these 20 leaks were not detected with mammography. With US, only one leak was not detected. US allowed more accurate prediction of the extent of free silicone in the breast and enabled detection of silicone within axillary nodes. Recognition of the characteristic highly echogenic sonographic appearance of microglobules of free silicone in the soft tissues can improve detection of implant rupture.