A biker who was on the ground having fallen off his motorbike after losing control was hit by another bike which fled the scene, the police said on Sunday.
They said the accident happened on the Coast Road in Naxxar at 11.45am.
The victim is a 23-year-old man who lives in Birkirkara. He had been riding a Honda.
He was given first aid by a medical team on site and then taken to Mater Dei Hospital by ambulance.
The police are on the lookout for the second biker.