Ambulance Victoria previously reported the 41-year-old was airlifted in a critical condition with a head injury.

On Monday morning a spokesman from The Alfred said the patient was in a stable condition.

Earlier, Sunday: A man has been charged after an alleged assault at Macarthur which saw another man airlifted to hospital with a critical head injury on Saturday.

The 48-year-old Portland man was interviewed on Sunday and subsequently charged with recklessly causing serious injury, recklessly causing injury, unlawful assault and affray.

Police allege a 41-year-old Penshurst man was seriously injured at the Music in the Vines festival.

The incident occurred while crowds were lining up to catch organised buses home, in the vicinity of the property on Mount Eccles Road, about 11.10pm.

Police said the victim was assaulted following a dispute between a number of people in the line.

An Ambulance Victoria spokesman said the man was airlifted to The Alfred Hospital in a critical condition with a head injury.

Three Portland men, including the 48-year-old and another two men aged 45, were arrested at the scene.

The younger men were released without charge, pending further inquiries.

The accused man was bailed to appear in a Warrnambool court on July 24.

The charges carry a maximum penalty of 15 years' jail.

Music in the Vines committee said it was "deeply saddened" by the incident which occurred after the festival came to a close.

"An incident occurred while patrons were waiting for organised buses home," the committee said in a statement.

"Security and support staff immediately attended and emergency services responded quickly to the situation."

Festival president Pieter Badenhorst said the committee was in contact with the victim's family and "their thoughts are with them all".

"On behalf of the committee we are thinking of the man and his family," he said.

"We are receiving updates and have offered the man's family our full support during this difficult time.

"Our sixth running of the festival was one we as a committee were extremely proud of, with patrons enjoying our family-friendly event."

Mr Badenhorst said it was "extremely sad that such an unfortunate incident has occurred".

"But we praise the response intervention from local police and emergency services," he said.

"The committee won't be providing any further comment at this time as the investigation is ongoing."

Warrnambool police crime investigation unit are appealing for anyone who was in the vicinity of the altercation or with information to come forward.

Anyone who witnessed the incident is urged to call Crime Stoppers on 1800 333 000 or log onto www.crimestoppersvic.com.au.