A spokesman for St John said the man was taken by ambulance to Lakes District Hospital.
Emergency services were called to the crash, at the corner of SH6 and McDonnell Rd, at 12.22pm.
A police spokeswoman said initial information was that a truck and a car had collided, and a third vehicle was then hit.
The road was partially blocked for a time, and northbound traffic was diverted down Hogans Gully Rd.
Tow trucks were called to remove the truck and a car.
The crash would be investigated, police said.