Since silicone is rapidly becoming one of the most commonly used biomaterials in modern medicine, pathologists will be observing increasing numbers of cases of silicone-related disease. Although numerous case reports have established that silicone elicits a characteristic response in tissues, the varying tissue reactions to silicone gels, liquids, and elastomers (rubber) have not been emphasized. Three cases are reported, and the literature is reviewed to illustrate the varying features of tissue reaction to silicone in its different forms. The first case is an example of silicone lymphadenopathy in an inguinal lymph node. This case demonstrates exuberant foreign body granuloma formation in response to particles of silicone elastomer. The second case involves a patient who had facial subcutaneous liquid silicone injections, and the third case is that of a woman in whom breast carcinoma developed 13 years after mammary augmentation with liquid silicone injections. These two cases illustrate the characteristic reaction to silicone liquid, with numerous cystic spaces and vacuoles in the soft tissues but minimal or no foreign body giant cell reaction. Scanning electron microscopy and energy dispersive x-ray analysis were performed in the first two cases, confirming the presence of silicon. Silicone migration and the clinical significance of various silicone-induced lesions are discussed.