The incident happen when the doctor and his wife returned to their car after having watched a late showing of a film at a cinema in Kortrijk (West Flanders).
Two unknown assailants asked the 63-year-old in Dutch to hand over his car keys.
The doctor refused and was hit several times with a truncheon. He was hit on the head during the attack and sustained a fractured skull.
He is currently in hospital where his condition is described as critical. His assailants took the car that was later found burned out in Villeneuve d'Ascq (Nord).