Eight fire engines and 58 firefighters and officers have been called to a fire at Chase Farm hospital on The Ridgeway in Enfield.
A small part of the ground floor of a two floored building is currently alight.
The Brigade was called at 2211 and is still at the scene. Fire crews from Enfield, Southgate, Edmonton, Chingford and Barnet fire stations are at the scene.
The cause of the fire is not known at this stage