Police were called to a property in Orangefield Close in Armagh at around 11.50 pm on Sunday, 29 April.
Upon arrival at the property, officers found a 32 year old man unconscious. He had sustained visible injuries to his face and body.
Inspector Gary Moore said “The victim was taken to hospital where his condition this morning is described as critical but stable.
“A 26 year old man was arrested at the scene on suspicion of GBH.
“He remains in custody at present.
“Our enquiries into this assault are ongoing and anyone who can assist us with our investigation is asked to contact police in Armagh on 101, quoting reference number 1473 29/04/18.”