Using the system, emergency-room doctors could scan unconscious or incoherent patients to quickly check their blood type and find out if they are taking any medications or have allergies or other medical conditions. Nurses could identify family members and determine whether patients are organ donors or have living wills. Surgeons could scan patients on the operating table to make sure they are working on the right person.

VeriChip Corp. of Delray Beach, Fla., is selling kits containing scanners and the large-bore needles used to insert the chips, and recommending that doctors charge patients about $200 each. The company has sold about 2,500 chips worldwide for use in people, and several hundred have been implanted, including about 100 in the United States, spokesman John Procter said. So far in the United States, however, most of the chips have been implanted into the company's own employees. Suspecting that many people are hesitant to get the chips until more emergency rooms are able to scan them, the company has begun giving scanners to hospitals for free, Procter said.