Four fire engines and around 25 firefighters were called to a fire at an administration building at the rear of the main hospital on Lewisham High Street in Lewisham.
Part of a storage room on the lower ground floor of the building was damaged by fire. Around 40 people left the building before the Brigade arrived. There were no reports of any injuries.
The Brigade was called at 2043 and the fire was under control by 2153. Fire crews from Lewisham, Greenwich, Forest Hill and Lee Green fire stations attended the scene.
The cause of fire is under investigation.