A man was assaulted in a house at the Watson Street area of Portadown in the early hours of Wednesday morning.
Detectives are appealing for information following the incident.
It is believed that three men entered a house sometime between 12.30am and 1.30am and assaulted the male occupant, who required hospital treatment for his injuries.
Detective Constable Colin Robinson appealled to anyone who may have noticed any suspicious activity in the area to contact Detectives at Lurgan on the non-emergency number 101, quoting reference number 49 17/08/16.
Alternatively, if someone would prefer to provide information without giving their details they can contact the independent charity Crimestoppers and speak to them anonymously on 0800 555 111.