Fire crews were called to the old Nithbank building on Lindsay Terrace at 4.26 pm on Wednesday night after flames and smoke were spotted coming out of one of the building’s lower windows.
Five fire engines attended the blaze as well as two other Scottish Fire and Rescue vehicles, an ambulance and a police van.
Firefighters were at the scene until 7.15 am yesterday morning.
A Scottish Fire and Rescue Service spokesperson said: “We were alerted at 4.26 pm on Wednesday, October 9, to reports of a well-developed fire within the ground floor of the former Nithbank Hospital in Dumfries and Galloway.
“Operations Control mobilised seven fire appliances and firefighters extinguished a fire affecting a derelict building.
“There were no reported casualties and crews left after ensuring the area was made safe.”
The sandstone building was similarly targeted in May last year when a fire devastated the front facing entrance and windows.
More recently the site has attracted attention from urban explorers Urbex Lost & Found who posted images to social media just weeks ago showing the building’s rundown and dilapidated state.
Police are now investigating the incident at the B listed building. Officers yesterday said they are treating it as a wilful fire. A Police Scotland spokesperson added: “Around 5.35 pm on Wednesday 9 October, 2024, we were called to a report of a fire at the derelict Nithbank Hospital, Dumfries.
“Enquiries are continuing into the cause of the fire which is currently being treated as wilful.”
