An alien implant is an object that a person believes was inserted into the body during an encounter or abduction experience. Reports commonly involve small lumps, fragments, or scars discovered after missing-time narratives, vivid dreams, or recalled medical procedures. The idea became a recurring element of late-twentieth-century abduction literature because it appeared to offer physical evidence for an otherwise private experience.

Podiatric surgeon Roger Leir became the best-known investigator of such claims. He and associates removed small objects from patients and described unusual magnetic behavior, biological coatings, radio emissions, or isotope ratios. Those findings circulated through books, conferences, and interviews, and more recent researchers continue to revisit the specimens. The claimed chain from a removed fragment to non-human intelligence, however, has not been established in a peer-reviewed, independently replicated record.

Published examinations have often produced ordinary explanations. Psychologist Susan Blackmore organized laboratory testing of one alleged implant that proved to be dental amalgam; she also summarized earlier specimens identified as biological material or commonplace fibers. Foreign fragments of glass, metal, carbon, or medical material can enter tissue without a remembered injury and may become encapsulated by the body. A strange appearance or uncommon composition is not enough to demonstrate manufacture or intentional placement.

A decisive implant case would require documented imaging before removal, sterile recovery, uninterrupted custody, full microscopy and isotopic methods, control samples, and independent laboratories able to repeat the result. It would also need evidence of engineered function, not merely an unusual elemental mixture. Until a specimen meets that standard, alien implants remain a contested branch of the biologics and non-human specimens debate rather than verified devices.