A man has been scalped during a violent home invasion on the New South Wales central coast.

Police say four men entered the Warners Bay home on Saturday morning and violently attacked the 35-year-old resident.

When his roommate returned home about 12 hours later he was found lying on the floor with severe injuries, including a fractured skull, facial injuries and other broken bones.

The resident was also scalped during the incident and it is believed he may have been tied up during the assault.

Emergency services took him to John Hunter Hospital where it is believed he will undergo surgery to re-attach his scalp.

It is not yet known whether the victim knew his attackers.

Police are appealing for anyone who may have witnessed anything unusual in the area about 1.30am on Saturday to contact Crime Stoppers on 1800 333 000.

All information is treated in strict confidence and callers can remain anonymous.