Investigations are underway into an altercation between two men outside the Malt Shovel Hotel on Anlaby Road, Hull shortly after 11.30pm on Saturday 19 August.
A 57-year-old man was taken to Hull Royal Infirmary for treatment to serious head injuries following the incident.
A 35-year-old man has been arrested on suspicion of assault and currently remains in custody.
Officers are currently on the scene working to establish the circumstances and are keen to speak to anyone who witnessed the incident.
Anyone with information is asked to call 101, quoting log number 710 of 19/08/17 or Crimestoppers anonymously on 0800 555 111.