A Melbourne taxi driver has been charged over a fare evasion accident in the city's north-east last night that left a passenger fighting for his life in hospital.

Police believe the injured Northcote man is one of two who attempted to flee a moving taxi on High Street in Northcote to avoid paying the fare.

"Both of these males have drunk a little bit over the evening, and young men out is the potential for all sorts of things to have gone on," Detective Sergeant Mark Amos said.

Police have been told two men entered the taxi about 1am at Queens Parade in Fitzroy North.

Police are appealing for witnesses to come forward. (9NEWS)

One man left the taxi near Clarke Street without incident, but the second man, aged 22, fell onto the road and hit his head near Mitchell Street.

A group of people nearby found the man on the road and called emergency services.

"He is in a critical condition, he has been in the operating room and is in our intensive care unit but has very significant injuries," Professor George Braitberg from the Royal Melbourne Hospital said.

It's believed the two men who fled the taxi had been drinking. (9NEWS)

A 35-year-old taxi driver from Footscray has been charged with negligently causing serious injury, dangerous driving causing serious injury and failing to stop.

He handed himself into Preston Police Station just after 7am this morning.

"I find it difficult to understand why you would risk life and limb for a few dollars," Sgt Amos said.