Matthew Tremain, 14, developed chronic kidney failure soon after he was born and his condition worsened as he grew older.
But dad Steve, 49, has now given him his left kidney in the hope it will allow him to lead a normal life.
Matthew's condition had left him often feeling tired and nauseous and hindered his social life, because he often felt too sick to leave the house.
Without a transplant, he would have faced perpetual visits to hospital for kidney dialysis.
The father and son went ahead with the operation despite knowing they could both die as a result.