The accident happened on the A82 Inverness to Fort William road, three miles south of Drumnadrochit at around 11.15am today.
The collision involved a motorbike and a Citroen Picasso car.
A Police Scotkabd spokesman said the biker was airlifted to Raigmore Hospital in Inverness by a Coastguard helicopter.
He added: “His injuries are believed to be life threatening.”
The road next to Loch Ness remains closed to allow an investigation to take place.
Drivers are advised to avoid the area and use suitable alternative routes.