Some people believe they have had alien implants inserted into their bodies. Typically, the subject also believes he or she is the victim of an alien abduction during which the surgery occurred. Claimed abilities of the implants range from mind control to location tracking (akin to humans tagging wild animals for study). This is called biotelemetry and it seems to have been applied within the MK-Ultra project, a secretive CIA mind-control research program.

Many skeptics argue against the idea of alien implants for a number of reasons, such as a belief that alien abductions are made up or the result of a mental illness on the part of the claimed abductee.