Eleven years after silicone implantation into the breasts a now 42-year-old woman developed arthralgia with a serological autoimmune phenomenon: antinuclear antibodies of the mottled type (titer 1:320 to 1:1,280), complement consumption, cytoplasmic thyroid antibodies (1:400), and constant elevation of erythrocyte sedimentation rate, concomitant with signs of silicone mastitis (angiotensin-converting enzyme 108 U/min; computed tomography demonstrated an infiltration in the right breast implant). As the patient has only quite minor symptoms she has so far refused removal of the implant.