Police in Pontypridd are appealing for any witnesses to an incident beneath the bridge over the River Taff in Broadway, to come forward.
An 18 year-old local male fell from horizontal steal supports which run beneath the bridge at around 3.30pm on Sunday, 17th August 2014.
He landed on rocks beneath and was taken to the University Hospital of Wales with a serious spinal injury.
A group of youths who were along the river bank at the time are helping police with their enquiries.
Any other witnesses are urged to contact South Wales Police via 101 or call Crimestoppers anonymously on 0800 555 111.