A man was knocked unconscious after being punched in a queue for the Tunes in the Dunes music festival at Perranporth on Saturday.
The victim was assaulted outside the Wateringhole Pub at around 10.45pm.
A 35-year-old man from Plymouth was arrested following the incident.
A police spokesman said: “Officers were informed that a man was assaulted whilst waiting in a queue at the Wateringhole Pub in Perranporth.
“The male victim was knocked conscious and a 35-year-old man from Plymouth was arrested and interviewed in relation to the matter. He was released on bail pending further enquiries.”
Anyone who witnessed the incident is asked to report relevant information via our website quoting reference 50230141153.