Teenager Jack Baker left his prosthetic hand gripped to handlebar of his motorcycle and went to his girlfriend for 10 minutes.
When he came back outside two hours later, the hand was gone, apparently taken by a thief or a prankster who found it more interesting to make off with than the bike.
"I came out and found the hand was gone. I thought it was my girlfriend's parents messing about, but they said it wasn't them," said Baker, 19.
"I went for a look around, but I couldn't see my hand anywhere. There were no kids about and no one to ask if they had seen it. I ended up jumping on my bike and going home."
The hand disappeared last week in Bristol, the city in southwestern England where Baker lost his right arm in a head-on crash with a bus in May.
The prosthetic hand allowed him to ride his new, specially-adapted motorbike, and Baker said he may not be able to afford the 450 pounds (US$903, 662 EUR) it will cost to replace it.