A vicious magpie attack has left a four-year-old boy blind in one eye in Toowoomba.

The boy, Seth McInnes, required around-the-clock treatment after the magpie swooped on him while he was riding a pushbike near playground equipment.

His father, Chris, said there had been no trouble with the magpies up until that moment, the Toowoomba Chronicle reported.

"He was riding his bike back towards me and I saw it (a magpie) coming down really fast," Mr McInnes said.

His father rushed to his son's aid when the magpie swooped and hovered near Seth's face.

"His screams didn't shoo it away, it was only when I got over there it left."

"He had a little scratch over his eye.

"But when I looked in his eye it was full of blood."

Chris was told his son would most likely lose all vision in his left eye after he had been rushed to Toowoomba hospital.

"He had to have four stitches in his eyeball," Chris said.

"It hit him right in the centre of his eye."

Chris urged all parents to take extra care, and hopes what happened to Seth would be a cautionary tale during magpie season.

"I knew it was magpie season," he said.