A subdermal implant is a foreign object surgically implanted beneath the skin. The term subdermal comes from the Latin sub (beneath) and the Greek δερμις (skin). The implant may be medical in nature, or it may be for technological purposes (see cyborg).

In science fiction (e.g., in the Otherland series by Tad Williams), subdermal implants are sometimes used as a form of cultural expression, similar to tattoos or other body modifications.

New surgical techniques in the Netherlands have allowed opthamologists to implant microthin metal shapes, such as stars and hearts, underneath the sclera of the eye, and thus visible in the white of the eye.