To prospectively evaluate the efficacy of ultrasonography in the diagnosis of ruptured silicone gel breast implants, 98 patients (192 implants) underwent preoperative breast ultrasonography prior to silicone gel breast implant removal. The prevalence of implant rupture confirmed at surgery in this group of patients was 62 of the 192 implants (32 percent). Of the 60 implants diagnosed as ruptured by ultrasonography, 46 were confirmed as having visible defects at surgery (true positive) for a positive predictive value of 77 percent. Of the 132 implants diagnosed as intact by ultrasonography, 116 were confirmed as intact at surgery (true negative) for a negative predictive value of 88 percent. Overall, the sensitivity of ultrasonography for implant rupture was 74 percent, and the specificity was 89 percent. These findings demonstrate that ultrasonography is an effective imaging modality for the diagnosis of silicone gel breast implant rupture. Compared with mammography, ultrasonography appears to offer superior sensitivity and specificity without radiation exposure or discomfort. Although magnetic resonance imaging has shown considerable promise in the diagnosis of implant rupture, ultrasonography provides comparable sensitivity at a fraction of MRI's cost.