At around 9pm on Saturday 1 July, a 40 year-old-man and a 46-year-old man were assaulted outside Haddenham Sports and Social Club on Woodways, Haddenham.
One of the victims sustained a lump and a cut to the side of his head and the other required surgery for a head injury. He also sustained a broken nose and a fractured skull. He has since been discharged from hospital.
Due to the injuries sustained, neither victim can remember the assault. The incident was reported to Thames Valley Police on 9 August.
No arrests have been made.
Investigating officer, Detective Constable Hannah Davison from Aylesbury Force CID, said: “These are two serious assaults, which left one of the victims requiring surgery.
“We have now launched a thorough investigation and as part of our enquiries, I would like to speak to anyone who witnessed the incidents or any suspicious behaviour in the area on this date."