An eight-foot boa constrictor was found in a field in Banbury last weekend.
The RSPCA was call out on Saturday by a member of public who had spotted the giant snake near a housing estate while out walking his dog.
The snake is 8ft 6inch long and weighs 12.2kg.
Deputy chief inspector Melanie Fisher said: “If anyone thinks they may know who this snake belongs to then we would urge them to get in touch with us by calling our inspectorate appeal line on 0300 123 8018.
“It’s hard to know for sure how this snake came to be in the field but I think the caller got a bit of a surprise. It’s not everyday you stumble upon an 8ft snake while out walking the dog.
“The snake may have escaped from a vivarium or may have been abandoned. Sadly she’s not microchipped so we do not know where she has come from. She is still in our care and is now doing really well despite the cold weather.”
She added the charity had seen a growing number of exotic animals being abandoned and had dozens of boas in its care. She urged people to do their research before buying a snake.
To help the RSPCA visit www.rspca.org.uk/give or text LOVE to 87023 to give £3 (text costs £3 + one standard network rate message).