A 29-year-old man was left injured after an alleged assault in Beverley in the early hours of Saturday.
He was leaving a pub on North Bar Within with friends, when he was approached by a man who allegedly attacked him around 2.15am.
Police said the injured man had been left "with what are thought to be serious injuries."
A 21-year-old man was arrested and released under investigation while enquiries continue.
Officers are appealing for information on 101, or witnesses can call Crimestoppers anonymously on 0800 555 111.