East Sussex Fire and Rescue Service received a call at 9.04pm with reports of a fire in the Holy Cross Care Home, in Lewes Road, Heathfield.
A fire spokesman said: “We sent three fire engines to the scene.
“Residents of the nursing home were in the building but they were all accounted for and no one had to be rescued.
“The cause of the fire is being treated as accidental.
“It started in the basement due to a faulty ventilation system.
“We used four breathing apparatus and two hose reels.”
All fire crews had left the scene by 10.50pm.