Six fire crews from Bourne, Billingborough, Grantham, Spalding and Donington, along with an aerial platform ladder from Boston tackled a blaze at a village pub which began just before 3pm.
A spokesman for Lincolnshire Fire and Rescue said there is severe fire and smoke damage to living space on the first floor of the Old Ship Inn, Pointon, but the ground floor of the pub appears to be intact.
He said the fire appears to be under control, but it is too early for crews to start working out what may have caused the blaze.
The pub was evacuated, leaving no risk to life.
At 6pm, five crews remained.
Motorists were warned to avoid the B1177 which was closed at Pointon from West Road.