Silicone-gel-filled breast implants have been widely used for breast augmentation and reconstruction after mastectomy. The rate of implant rupture and its sequelae are not known. We review the frequency, causes, sequelae, and detection of implant rupture. Materials testing of removed implants provides evidence that as implants age in vivo, they weaken and may rupture. Sequelae of rupture include migration of gel accompanied by inflammation and silicone granuloma formation. The role of free silicone gel in relation to idiopathic or atypical connective tissue disease is not clear. Magnetic resonance imaging is substantially more sensitive in the detection of rupture than is mammography or ultrasonography.