Animal welfare officers are investigating after a group of boys was spotted throwing and kicking a dead boa constrictor around city streets.
A member of the public reported the "mystery" incident which happened in the Ely area of Cardiff on Friday and bagged the dead snake so it could be examined by the RSPCA Cymru.
The charity said it was not clear whether the snake had been dead or alive at the time of the incident, but that a vet who examined the carcass believed it had been dead for around 24 hours.
The vet also reported the reptile was underweight.
RSPCA inspector Gemma Black said: "This incident is a bit of a mystery - and it is unclear whether the snake was dead or alive when it was spotted being kicked and thrown in the Ely area of Cardiff.
"We're unsure how this snake came to be out on the street in Ely and whether this is simply an escaped snake which sadly died, or whether something more sinister has taken place."
The charity is urging anyone with information about the snake to call its confidential inspectorate appeal line on 0300 123 8018.