Teenager assaulted at Wetherspoons in Louth
The victim is believed to have been hit with a glass or a bottle and sustained a facial injury.
A man in his 20s was arrested and has now been released under investigation.
Lincolnshire Police would like to hear from anyone who was in the pub and witnessed what happened.
Anyone with information should call 101, or report anonymously to Crimestoppers on 0800 555 111.