Catering staff, cleaners and porters are amongst the hospital workers taking strike action in Bolton over pay.
The staff are employed by a private company called iFM Bolton - which is wholly-owned by Bolton NHS Trust.
The employer had agreed to pay staff the NHS rate for their work, but has now gone back on that promise.
Workers doing the same jobs in other hospitals do get paid the correct NHS rates.
The staff do important jobs in the hospital and they are determined to get the NHS pay rates that they were promised and deserve.
The strike action began at 7am on Thursday 11 October and runs for 48 hours.
There will be a rally at Victoria Square in Bolton from 12noon on Friday 12 October.
Here are some photos from the picket lines: