Twenty-six women had a systemic disease with central nervous system (CNS) involvement at a mean age of 39.2 years (range, 23 to 64 years) after receiving silicone breast implants (n = 25) or silicone fluid injections into breasts (n = 1). The median latency period between breast surgery and onset of symptoms was 5.71 years (range, 3 months to 15 years). All patients had evidence of disseminated CNS lesions; 20 patients also had evidence of peripheral neuropathy. Additional problems included myalgia (n = 24), joint stiffness (n = 23), arthralgia (n = 22), sicca complex (dry eyes and dry mouth) (n = 19), headache (n = 16), skin rash (n = 15), joint swelling (n = 14), Raynaud's phenomena (n = 14), fever (n = 13), hair loss (n = 12), allergies (n = 11), sensitivity to sunlight (n = 10), and lymphadenopathy (n = 9). Magnetic resonance imaging brain scans were abnormal in 22 of 26 patients (21, white matter lesions; 1, ischemic lesions; 4, cerebral atrophy). Spinal tap revealed oligoclonal bands in 18 of 23 patients. Visual evoked responses were delayed in 14 of 23 patients, and autodirected antibodies were detected in 16 of 26. Sural nerve biopsy results showed loss of myelinated fibers in 15 of 15. Seventeen of 24 patients (71%) who had implant removal were found to have grossly ruptured implants. We believe our patients had a new syndrome triggered by the foreign material in their body. This syndrome appears as a systemic inflammatory autoimmune disease with central nervous system involvement resembling multiple sclerosis.