Surrey Police were called to Cobham High Street close to its junction with Hogshill Lane shortly after 4.30am today, after a man believed to be in his 50s was found with a serious head injury.
Police said the circumstances leading to the man's injury are unclear at this early stage, but they were not caused by a traffic collision.
He has been taken to St Peter's Hospital, Chertsey, where his condition is described as potentially life-threatening.
The High Street was closed for several hours between Church Street and Hogshill Lane and reopened at about 8.30am.
Police, who were called to scene by the ambulance service, are still investigating the circumstances and no update is anticipated for a few hours.
If you have any information about how the man's injuries were caused or were in Cobham High Street between 1.30am and 4.30am please call Surrey Police on 0845 125 2222 or Crimestoppers anonymously on 0800 555 111.
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