Detectives in Lurgan arrested an 18 year old male after a man suffered serious facial injuries during an assault on Sunday, 10 November.
Police said a 22 year old man was assaulted at a house party in the early hours of 10 November.
The incident happened in Ballynamoney Park, Derrymacash.
The 18 year old was later released on bail pending further enquiries.
Police are keen to speak to anyone who witnessed the assault or was in attendance at the party and can be contacted in Lurgan on 0845 600 8000. If you prefer to provide information without giving your details you can contact the independent Crimestoppers charity anonymously on 0800 555 111.